Only plays music stored on your device

Unfortunately the app only allows to play music that is stored on your device. Does not work with Apple Music, Spotify or any other cloud based services.
Also, it would be nice if the sound manipulation was systemwide, not just during use within the app, but all sounds and conversations or videos one listens to on the iPhone or iPad.
I cannot use the app since I have no music stored on my phone and need the space for other things.

Volker Lauterbach about Tinnitus Pro : Music Therapy, v1.2.2