A Study to Evaluate the Effect of Sodium Zirconium Cyclosilicate on Chronic Kidney Disease (CKD) Progression in Participants With CKD and Hyperkalaemia or at Risk of Hyperkalaemia

Inclusion Criteria: * Capable of giving signed informed consent which includes compliance with the requirements and restrictions listed in the ICF and protocol * Must be ≥ 18 years of age at the time of signing the informed consent. * Must have eGFR ≥ 25 and ≤ 59 mL/min/1.73m2 as calculated by central laboratory (CKD-EPI formula) at screening (Visit 1) * Must have UACR ≥ 200 and ≤ 5000 mg/g as calculated by central laboratory at screening (Visit 1). If the first sample does not fulfil eligibility criteria, a second sample can be obtained during the screening period; if so, the UACR measurement from the second sample must be within the eligibility range. * Any of the following criteria, a or b, at screening (Visit 1): 1. Cohort A: Hyperkalaemia (S-K \> 5.0 to ≤ 6.5 mmol/L) as measured by the central laboratory, and on adequate\* or limited\*\* RAASi therapy due to hyperkalaemia. 2. Cohort B: Normokalaemia (S-K ≥ 3.5 to ≤ 5.0 mmol/L) as measured by the central laboratory and on limited\*\* RAASi therapy due to high risk of hyperkalaemia. High risk of hyperkalaemia is defined as: (i) Participants with a previous medical history or record of hyperkalaemia within the prior 24 months, who are on limited\*\* RAASi therapy despite indication in CKD. (ii) Participants in whom RAASi therapy is indicated in CKD, who are on limited\*\* RAASi therapy and have S-K ≥ 4.7 to ≤ 5.0 mmol/L. (iii) Participants in whom RAASi therapy has been discontinued or reduced to suboptimal\* doses because of hyperkalaemia. \*Adequate RAASi dose levels are defined in protocol; doses lower than these are considered as suboptimal. \*\*Limited RAASi therapy is defined as no or suboptimal RAASi therapy according to dosing guidance provided in protocol. * If on thiazide or loop diuretics, the dose must have been stable for 2 weeks prior to screening (Visit 1). * If on RAASi therapy, the dose must have been stable for one month prior to screening (Visit 1) and remain stable during screening. * If on an SGLT2i treatment (ie, dapagliflozin and canagliflozin), finerenone, or any other medications in these 2 classes that are approved for CKD, the dose must have been stable for 3 months prior to screening (Visit 1). * Participants must be one-year postmenopausal, surgically sterile, or using one highly effective form of birth control (defined as one that can achieve a failure rate of less than 1% per year when used consistently and correctly). They should have been stable on their chosen method of birth control for a minimum of one month prior to screening (Visit 1) and willing to remain on the birth control until one month after the last dose of study intervention. Exclusion Criteria: * New York Heart Association class III to IV congestive heart failure at the time of screening (Visit 1) or previous history of severe or symptomatic heart failure. * Myocardial infarction, unstable angina, stroke, or transient ischaemic attack within 3 months prior to screening (Visit 1). * Participants with a known history of systolic blood pressure ≥ 160 mmHg or diastolic blood pressure ≥ 95 mmHg within 2 weeks prior to screening (Visit 1) are excluded. In addition, any participant with systolic blood pressure ≥ 160 mmHg or diastolic blood pressure ≥ 95 mmHg as measured at screening (Visit 1) and confirmed by repeated measurement is excluded. Participants may be rescreened once blood pressure is controlled. * QTcF \> 550 msec at screening (Visit 1). * History of QT prolongation associated with other medications that required discontinuation of that medication. * Congenital long QT syndrome. * Symptomatic or uncontrolled atrial fibrillation despite treatment, or asymptomatic sustained ventricular tachycardia. Participants with atrial fibrillation and heart rate controlled by medication are permitted. * Lupus nephritis or anti-neutrophil cytoplasmic antibody-associated vasculitis. * Change in renal function requiring hospitalisation or dialysis within 3 months prior to screening (Visit 1). * History of renal transplant (or anticipated need for renal transplant during the study). * Severe hepatic impairment, biliary cirrhosis, or cholestasis. * History of hereditary or idiopathic angioedema. * Any prior hypersensitivity to ACEi or ARB that in the investigator's judgment precludes use of lisinopril and valsartan/irbesartan. Prior hypersensitivity reactions to consider include, but are not limited to, development of angioedema, icterus, hepatitis, or neutropaenia or thrombocytopaenia requiring treatment modification. * Known hypersensitivity or previous anaphylaxis to SZC or to components thereof. * Any condition outside the CV and renal disease area such as, but not limited to, malignancy, with a life expectancy of less than 2 years based on investigator´s clinical judgment. * Active malignancy requiring treatment at the time of screening (Visit 1), except for successfully treated basal cell or treated squamous cell carcinoma. * S-K \> 6.5 or \< 3.5 mmol/L by local laboratory within 1 day prior to the scheduled first dose of SZC in the initiation phase. * Evidence of COVID-19 infection within 2 weeks prior to screening (Visit 1). * Treated with dual blockade of RAAS (combined use of an ACEi and ARB) within 3 months prior to screening (Visit 1). * Treated with an angiotensin receptor neprilysin inhibitor (ARNI; sacubitril/valsartan \[Entresto®\]) within 3 months prior to screening (Visit 1). * Treated with an MRA not approved for CKD within 3 months prior to screening (Visit 1). * Treated with aliskiren-containing products with 3 months prior to screening (Visit 1). * Treated with SPS (eg, Kayexalate, Resonium), CPS (Resonium Calcium), patiromer (Veltassa®), or SZC (Lokelma®) within 7 days prior to screening (Visit 1). * Participation in another clinical study with an investigational product administered within one month prior to screening (Visit 1). * Not willing or not able to change to lisinopril or valsartan/irbesartan, the protocol-mandated RAASi study intervention. Note: For participants taking a fixed combination of an ACEi or ARB with another agent (eg, calcium blockers or diuretics) as SoC, the investigator must make a judgment that it will be safe and efficacious for such participants to change to the study ACEi or ARB and to the other drug as separate agents. * Previous dosing with SZC in the present study. * Currently pregnant (confirmed with positive pregnancy test at screening \[Visit 1\]) or breastfeeding. * Judgment by the investigator that the participant is unlikely to comply with study procedures, restrictions, and requirements. * Involvement in the planning and/or conduct of the study (applies to both AstraZeneca staff and/or staff at the study site).