Uh... I can't download it on my android...
Viewing post in Drain Mansion - Free Version comments
If that happens you have to first uninstall the game, then reinstall it. But beware, this WILL delete your save file. I'd recommend you to back it up first. It's in Android/data/com.Kredyn.DrainMansion/files on the internal storage of your phone. Then after you installed it, put the save file back. It is backward compatible.