No one is going to help you with the setup
This is the foremost and most important thing to keep in mind. WhatsApp is never going to help you with setting up WhatsApp pay. It won't ask you for any payment-related details, bank account, or any other information.
If you want to use WhatsApp pay, you will have to set it up on your own; also, it is an easy process, thus, never believe anyone who calls or messages you claiming to help you with setting up the payments feature on your smartphone.