Add Payment Method
Before any customer can be added to a Payment Stream, they must have the billing address filled in and have a payment method entered on their customer card. This can be done 2 different ways.1) When you add them in manually, they can provide the payment information to you to be entered into their record.
2) You can send them an email with a link so they can sign into the secure customer site and add/update the information themselves. (Refer to the 'Create Customer Login' article)