You don't need to do anything! As the last step of the quote process, the prospect will have a choice to pay monthly or pay in full for their subscription with a credit card. If they select monthly payments, that card will be billed monthly. You or they can edit or change the credit card from the Agent Portal or the Member Portal at any time after they make their initial payment.
Here's what the prospect flow looks like.
If your prospect is having trouble completing the quote flow, please contact us.