“Payment cards are not supported for this account” issue

Correct, because you device shares information about your location and that generates and automatic response to the request, pressing the plus button. You can search it online and you can also search the first links I gave you. I’ll post them again for your convenience.

Are you in a country or region that supports Apple Pay?

Countries and regions that support Apple Pay - Apple Support

Does your financial institution support Apple Pay?

Apple Pay participating banks in Asia/Pacific, Africa, Europe Latin America, Middle East and United States - Apple Support

Your bank is not listed as being supported.

I’m not asking if your country or bank is supported. It’s the age requirement that different countries impose through their banking laws and regulations.

If your child has an Apple ID, Apple knows their age. If the age is below the minimum requirement for your country, Apple does not support adding a payment method to their Apple Wallet.

The point is, the law may allow a child to have an account but not allow them to add it to an electronic wallet. I don’t know for certain, but your bank most definitely will know. Apple sets its minimum at 13, but individual countries may impose stricter limits. Your bank should know whether they permit it or not and the minimum age requirements. A simple phone call to your bank should resolve the issue.

You will probably need to ask the bank that issued the card and inquire about their age restrictions. Many countries, especially in Europe, have a higher age restriction than Apple’s minimum age.

You’re welcome. I hope you have a great day, too!