I landed here after searching for the same problem. This might help:
My original password, from the website login, includes a comma. But, I experimented and figured out that the Android app's login screen does not accept commas as valid password characters, so it says my password in invalid. If I omit the comma when I enter my password, it does does not reject it as invalid (but of course it won't let me log in because the password is wrong without the comma). I'll have to change my password so it will work in both places.
By the way, I was also able to use my license key to log into the Android app.