@DVDandroid: There is a bug while using SDK 25: Tap on download a some module shows the download progress, but after that there is a message it could not be saved & installed due to permission problems. Take a look with an explorer in the folder of the message shows the apk is not availble. I think another cache-directory should be used with proper permissions, eg get[External]CacheDir()
All with problem a newer version of a module is not visible: In Android settings force close the app, clear cache (of the app) and then open it again. This is the same bug the kitkat-installer still has!