You can allow a customer to register and check out with a class without paying by credit card, by creating a discount code for 100% off to bypass payment. You can give the discount code a descriptive name like "CASHFALL2019" to track its use from the Custom Rosters.
Create a discount code by going to the Provider Dashboard > left menu > Registration Setup > Discounts, and go to the Discount Codes tab. Then click on the "Add Discount Code" button. Be sure to select the correct Unit and Amount. When you are done, click on the "Save" button. You will then need to give this discount code to the customer.
On the Discount Codes page, you can see how many times a Discount Code has been used under the "Usage" column.
To see who has used this Discount Code, you will need to look at a Custom Roster. You can access Custom Rosters by going to the left menu > Roster & Analytics > Rosters, and click on the "Custom Rosters" tab. Then click on the "Create a New Custom Roster" button, make changes to the parameters in Step 1 if needed, and click on "Next". In Step 2, be sure to check "Discount Code" and "Discount Code Amount", along with any other information needed to identify the customer.