Savings Customer Cards on File Toggle Not Working

Question:
I charge a deposit for booking a service and use POS hardware to swipe the customers card in person when they arrive. Many customers would prefer I simply charge the remaining balance as some are arriving without their cards. I have toggled the option on in my settings but checkout is not showing the option. Is there some other requirement I am missing?

Product:
Wix Checkout

What are you trying to achieve:
Save customers card on file to charge the balance of booking (services)

What have you already tried:
I have the toggle set to on that is supposed to give my customers the option to save their cards on file as they checkout

Additional information:
I elected not to have customers sign up as members and am wondering if that is necessary to utilize this function or if I am missing something else