Go to your company panel, then to Service Types, add a new service (add rate button) or select the one that is already active and enable the option of payments with credit and debit card.
Download the passenger app and add a card with the next credentials:
Card #: 4111 1111 1111 1111
Exp. date: any date
CSC or CVV: Any 3 digits.
Same demo card you can add in driver app for the demo driver top ups and more.