Split Pay works with Visa and Mastercard debit cards — Discover and credit cards aren't supported. If you don't have one, here are your options:
Check with your bank first. Nearly every checking account comes with a Visa or Mastercard debit card. If you never activated yours or don't have one, your bank can usually issue it free — and many banks give you a virtual card number in their app that you can use right away, before the physical card arrives.
Look into a virtual debit card. We're not able to recommend a specific company, but many financial services offer virtual Visa or Mastercard debit cards that link to your existing checking account — no new bank account needed. We recommend searching "virtual Visa or Mastercard debit card" in Google to find an option that fits your needs. Before you sign up:
Make sure it issues a debit card (not credit) on the Visa or Mastercard network
Check the provider's fees
Leave a few business days for account verification — don't wait until right before a payment is due
Once you have a card, add it under Account → Change Debit in the app or at splitpay.com.
See also: Why isn't Discover accepted?