The Embedded UI page now documents how AeroPay behaves in sandbox: the MFA SMS is real and goes to the user's phoneNumber, sandbox accepts 000000 as the MFA code, a verified phone number is required for the deposit-aeropay / withdraw-aeropay permissions, and bank linking uses the Aerobank test bank (sync / no_mfa). It also explains that "AeroPay unavailable" errors carrying a Type | Code | Message line are Aerosync's own messages passed through from the widget. Matching entries were added to Error Codes and the Frontend Integration Guide FAQ.