Environments observed
App version : alpha (2017-08-28)
Android version : 4.3
Device vendor : Samsung
Device model : GT-I9300

The environment (Android 4.3) is more important for this to reproduce.

A. Download progress not recognised: App doesn't show progress for a compilation whose download is in progress. Instead it shows the options (after some time) as if the download has been completed when it hasn't.

B. Downloading compilations twice: I'm able to download the compilation twice when the network is slow by doing the following,

1. Go to the compilations list
2. Tap on the overflow icon of a compilation
3. Tap on the 'Download' button
4. Immediately go to the details view of the compilation for which the download button was tapped
   1. You should see be seeing the Download button (in activated state) on the screen as the network is slow and the app hasn't recognised the download yet. If you don't that implies that the network is fast.
5. Tap on the 'Download' icon

C. Cancelling a download makes the app to malfunction
WARNING: You would have to clear the app's data to access the 'Offline Library' again

1. Download a compilation
2. Cancel the download using the download manager
3. Close the app
4. Try to go to the 'Offline Library' screen.

That would result in the app showing a black screen and nothing else whenever you try to access the 'Offline Library'. The same behaviour is observed when the download fails for some reason.