Teya and Viva Wallet
Card payments use Teya or Viva Wallet. Both are connected from owner settings, and integrated card payment has to be switched on.
Teya
Generate a device code in settings. Approve it in the Teya app, or open the verification link. The till can then send a bill to a Teya card machine. A card refund for that sale goes back through Teya.
Viva Wallet
Press Connect Viva Wallet. Viva opens onboarding in a new tab. When the account is connected, the till can take a card payment on a Viva terminal, and a refund can be sent back through Viva.