I reached out to support, and they said the following: “Unfortunately there was a problem with the latest release of Moves by Maxon that caused some users to be unable to log in. However, please keep an eye out for updates on the AppStore as a fix for this issue is currently in Review by Apple and should be released soon.”
That was on Dec 21, when you last tested, so I presume the update had gone through. Unfortunately, the app is essentially dysfunctional for the following reasons:
1) At least with the PC version of C4D R25 using the Moves by Maxon extension(latest), the computer and iOS device are unable to see each other on port 52473, even if explicitly opened in the firewall. Furthermore, there is no longer an option to use a QR code for registration (it has been removed).
2) The iOS app on an iPad Pro 2021 shows significant lag in motion capture. It is currently unusable due to a pronounced .5-1 second delay at every 30 frames or so.
3) Body capture mode does not work at all (no body is recognized, regardless of what the camera is seeing).
I would recommend more rigorous testing before releasing updates. All of these functions were operable in the last version.