Using a saved credit card - mundipagg/magento2 GitHub Wiki
Using a saved credit card is simple as using a new one. To do so, your logged customers should follow the steps below:
- The customer should log in your store and proceed to the checkout screen as usual.
- When filling an credit card form, they will see the Select a Card select. They just need to select a card from it:

- After that, they need to fill the Installments select and continue the checkout normally:
