How can I create an Apple Pay account?

There’s no such thing as an Apple Pay account. Do you mean Apple Cash account? Please review the Apple Support article I linked to below and see if that’s what you want. If it is, follow the instructions in the second link to open your account.

Apple Cash - Apple

Use Apple Cash in Wallet on iPhone - Apple Support

Apple Pay is not an account that can be created. It is simply to securely process a transaction with the cards in your Wallet, so the merchant does not know your account number. Do you mean maybe Apple Cash or Apple Card?