I just spent a half hour with Garmin tech support getting it working on my Android device. Here is what I learned:
1) Screen name - needs to be unique but no error message other than cannot log into the app. Garmin is going to correct now that we figured that out, but it might take a few days. So, best not to use your first name unless you append a bunch of random numbers.
2) If you don't have Garmin charts, the base map is barely usable, with many of the AC icons quite far inland instead of near where they should be. Without a Garmin Android app, the new AC app seems only to be useful if you have a Garmin chartplotter to pair it with.
I will be sticking with the AC web live map for now...