Try these steps to set up a card on your account:
First,
Click the “Payments” tab at the top of self-serve.
Then, click “manage my card”
Finally, select one of the options (Yours should display an option to register a card, mine has an option to update because my card is already registered.
If this does not work, what platform are you accessing your account on?
And to confirm, have you already set up your account and selected a plan?
I hope this helps 🙂
