Inclusion criteria:  Male and female patients 18 years to 75 years (both inclusive) of age on the day of signing informed consent. Patients diagnosed with biopsy proven primary Focal Segmental Glomerulosclerosis (FSGS) or documented Transient Receptor Potential Cation subfamily C Member 6 (TRPC6) gene mutation causing FSGS prior to screening visit. Average Urine Protein-Creatinine Ratio (UPCR) ≥ 1500 mg/g based on two 24-hour urine samples collected at least 7 days apart at screening. Completion of initial corticosteroid therapy course (if applicable) or discontinuation due to intolerance before entry to the trial. If applicable, corticosteroid therapy (i.e. prednisone) of ≤15 mg/day or ≤30 mg on alternate days with stable dose for at least 2 weeks at randomization, with no plan to change the dose during the study. Patients treated with Angiotensin Converting Enzyme (ACE) inhibitors, Angiotensin II Receptor Blockers (ARBs), finerenone, aldosterone inhibitors, or Sodium-Glucose Cotransporter-2 (SGLT2) inhibitors should be on a stable dose for at least 4 weeks prior to screening visit with no plan to change the dose during the study. Body Mass Index (BMI) of ≤ 40 kg/m2 at screening visit. Women of childbearing potential (WOCBP ) must be willing and able to use highly effective methods of birth control per International Council on Harmonisation (ICH) M3 (R2) that result in a low failure rate of less than 1% per year when used consistently and correctly. A list of contraception methods meeting these criteria is provided in the informed consent form (ICF) and in the study protocol. Men must be willing and able to use condom if their partner is a WOCBP.  Further inclusion criteria apply.  Exclusion criteria:  Known monogenic (with the exception of TRPC6 gene mutations) or clinical or histologic evidence of secondary FSGS. Documented Alport syndrome, Nail Patella syndrome, diabetic nephropathy, Immunoglobulin A (IgA)-nephropathy, lupus nephritis, or monoclonal gammopathy (e.g., multiple myeloma). Concomitant use of calcineurin inhibitors. Concomitant treatment with cytotoxic agents (cyclophosphamide, chlorambucil), or CD20 monoclonal antibody, e.g., rituximab, within 5 half-lives before screening visit.  Note: use of other immunosuppression therapies considered as standard of care may be allowed as long as the patient remains on stable therapeutic dose throughout the study.  Estimated glomerular filtration rate (eGFR) < 30 mL/min/1.73 m2 (Chronic Kidney Disease-Epidemiology Collaboration (CKD EPI) formula based on serum creatinine and cystatin C) at screening visit. Time between start of the Q-wave and end of the T-wave in an electrocardiogram (QT) intervals corrected for heart rate using the method of Fridericia (QTcF) greater than 450 milliseconds (ms) in males or greater than 470 ms in females, or any other clinically relevant electrocardiogram (ECG) findings (at the investigator's discretion) at screening visit. Detection of graded cataract by Lens Opacities Classification System (LOCS) III higher than NC1/NO1, C0, P0 in the slit lamp eye examination at screening visit. Planned cataract surgery during participation in the study. Patients with cataract who have undergone lens replacement are not excluded. Women who are pregnant, nursing, or who plan to become pregnant while in the study.  Further exclusion criteria apply.