Update - This error was resolved. I'm not exactly sure on the root cause but in case anyone hits the same issue -
1) I reinstalled the myAudi app on the phone a few times
2) Logged into myAudi on a different phone (iPhone) and connected the iPhone to the car - got the same error
3) Logged in again to the app on Android and it worked!
The above steps may be a coincidence but worth a shot.