The downloader will download the full game's assets into its own android namespace.
You won't have a new app.
Once the download is complete and you reach the "The game will/should restart by itself once done." screen, the downloader will need to compile all the new files.
It's a huge game and regarding your device, it will take some time ( ~5/10 min).
This operation is performed during the stuck "loading" screen.
Subsequent launches will be faster.
I need to work on the UI to give more insight to the user, but I haven't found the time at the moment.