Can not add a credit card for my Apple Pay!!! So annoying

See if this helps:

Set up Apple Pay - Apple Support

Note that ApplePay does NOT universally support all regions; and not all card issuers within a supported region choose to participate.

Pay close attention to the links within the article listing the Supported Regions and Participating Banks.

You don’t give us much information to go on such as - which iPhone do you have, which iOS, what trouble shooting steps have you tried? You may find this link helpful.

If you can't add a card to Apple Wallet to use with Apple Pay - Apple Support

The most important thing to know is this — Apple does not approve or decline cards for use with Apple Pay. If your card was declined, contact your bank or card issuer.