Can’t set up apple pay

See→Set up Apple Pay - Apple Support. Especially note this statement in that link:

Learn if your country/region supports Apple Pay. To check if your card is compatible with Apple Pay, contact your card issuer.

Are you seeing a message when adding a card to your Apple Wallet? Such as Could Not Add Card, Invalid Card or Card Device Limit? There are a few things to keep in mind when adding a card to your Apple Wallet:

• Contact your card issuer to see if they support Apple Pay.
• Update to the latest version of iOS
• Confirm that you have Face ID or a passcode set on your device.
• Make sure that you are in a supported country or region.
• Check that your device is compatible with Apple Pay.

Refer to If you can't add a card to Apple Wallet to use with Apple Pay - Apple Support for more information.