Have you received the terms and conditions via the Wallet app and agreed to them? The card verification is done in two parts. The first part just verifies that the account is active, in good standing, within expiration date etc. When the confirms the account, Terms & conditions are sent and when you agree to them, the more thorough verification process begins. Your card is being >Red Flow or Red Path< and is failing verification.
The verification includes location services data, Apple ID data and device data. Is the iPhone new, or used and new to you? Is the Apple ID new or have you been using it for a while? Are you logged into iTunes and Apple App Store?
Have you reported any fraud on any of your accounts? Banks share information in regard to fraudulent use. In other words, something reported 6 months ago on a different credit card, issued by another bank, could still prevent this card from being added.
The verification process, is ultimately up to the bank that issued the card. But three entities are involved, issuing bank, Payment Network Operator (Visa, MasterCard etc.) and TSP (Token Service Provider). Any one of them could be preventing the card from being added to your wallet.
Apple provides basic data, but it’s anonymous to Apple meaning they have no way of examining the data. The parties involved analyze the data using proprietary algorithms designed to detect potential fraudulent accounts being added to an electronic wallet.
Once the PNO and bank authorize the account for Apple Pay, the TSP generates a token and encrypts it and sends it to Apple servers that then added the token to Secure Element and Secure Enclave. Once the token is in the Wallet app, your payment method is ready to use with Apple Pay.
You need to ask the bank why they are red pathing or red flowing your account? It could be the PNO or TSP, but only the bank can open up a support ticket with them and seek a resolution.