I uninstalled and reinstalled koala - where are my songs?

ANDROID

Unfortunately once you uninstall, Android OS will remove all the files unless you remember to tick the box that says “Keep app data.” in the message that comes up.

So tick the box if you want to keep your songs.

iOS

Also unfortunately, when you delete an app on iOS it deletes its data with the exception of iCloud data, as very clearly stated in the message.