ADE for android 2.2.1?

I don't think you can choose, as the only available version is the one on Play Store, 3.1. I would be interested in how you get on with it, as it is nothing like the Windows version. In particular, if you are thinking of using it to download and transfer books to, say, a Kobo, I have not been able to get it to work. It does work as a reader.