Hi Deriam69,
To help troubleshoot, let's have you take the following steps:
If you can't add a card to Apple Wallet to use with Apple Pay - Apple Support
1) Check that you're able to use Apple Pay:
*Contact your card issuer to see if they support Apple Pay.
*Update to the latest version of iOS or iPadOS, watchOS, or macOS.
*Make sure that you are in a supported country or region.
*Check that your device is compatible with Apple Pay.
2) Check for services outages or connection issues.
3) If you see the message "Could Not Add Card" or "Invalid Card," contact your bank or card issuer.
Apple does not approve or decline cards for use with Apple Pay. If your card was declined, contact your bank or card issuer.
If you need help adding a card, learn how to set up Apple Pay.
We recommend the steps above because they can help troubleshoot the issue you're experiencing trying to add your new debit card to Apple Wallet.
Please do not hesitate to reach back out to us if you have additional questions.
Thanks for using the Apple Support Communities.
Cheers!