Spot requires a secret PIN to confirm and process QR code payments - like any other app. When a group account is created, the owner of the account needs to share the PIN with members of the account.
Without the PIN, no QR code payments can be made.
Oooh, on that note, only the account holder, so, not a member, is able to set and reset secret PINS.
If you want to read our full shared account Ts&Cs, you can check them out here