For Apple Pay testing, I have tried the following: Sign into the Sandbox Account via Developer Settings: Settings > Developer > Sandbox Account Keep your main Apple ID for everything else Add Test Cards to Wallet: Try adding the test card numbers (MasterCard and Visa Debit, as we support only those) Apple provides in their documentation. Unfortunately, none of them are added to the wallet. All the time it gives 'Could Not Add Card'. I tried on devices with iOS 18+. Can anyone advise on this? Thanks