Android doesn't recognize *.caf files as an audio format, as they are part of the Apple ecosystem.
Popular media players such as VLC are able to play these files, but the commonly used Android API for
retrieving the MIME type of files
doesn't know about that and returns 'unknown type' (
Download the latest apk from releases
The App doesn't show up in the launcher, uninstall it from the "Apps"-Menu in Settings
Build like any other android project, nothing fancy here...