Not able to add debit or credit card to my wallet

Check all of the instructions here if you cannot add a card to Apple Pay. There are several steps to be taken, one of the first is to ensure that the location you are in supports Apple Pay. If you can't add a card to Apple Wallet to use with Apple Pay - Apple Support

Here are the steps to take when you wish to set up Apple Pay and add a credit card. Set up Apple Pay - Apple Support