Read this document about how to view your current payment types and add Apple Account payment methods on an Apple mobile device, a Mac, or a PC --> Add a payment method to your Apple Account - Apple Support
If an item appears in red then it is not working. Apple is likely querying your bank and not receiving a "yes" message or any message at all. In that case the best place to start is with your bank. It could even be the system is down somewhere. For Apple's end use this link to check the status of Apple’s various services and servers —>
Apple - Support - System Status
This support article has various country telephone numbers for contacting Apple for support and service ➔ Contact Apple Support - Apple Support Scroll down to “Connect with live support”. If your country is not in the list, go to the “Other countries” entry at the end of the list. Not every country has telephone support, and phone numbers may only work when calling from the same country.
For chat, you can try using the Apple Support App —> https://apps.apple.com/app/apple-support/id1130498044
For chat help with a USA Apple Account —>
https://getsupport.apple.com/?caller=kbase&PGF=PGF63005&category_id=SC0998&symptom_id=20198