Payments in the staging environment use Stripe test cards.
No real financial transactions are processed.
You can find a full list of supported Stripe test cards in the official Stripe documentation:
Stripe Test Cards
Use the following Stripe API key to tokenize credit card information: pk_test_51LgDhrHGDlstla3fdqlULAne0rAf4Ho6aBV2cobkYQ4m863Sy0W8DNu2HOnUeYTQzQnE4DZGyzvCB8Yzl1r38isl00H9sVKEMu