[4.5.0.16][10II] Android App Spotify is not able to use SD Card

I think I have another issue…
What I did so far:

  1. try chmod 777 everything within ~/android_storage (no success)
  2. try chown 501078.501078 everything within ~/android_storage (no success)
  3. deleted everything within ~/android_storage (no success)
  4. deleted folder “Android” in SD card (no success)

Maybe some general questions:

  1. Which user and group should be set to the data on the SD card and which access rights?
  2. What is the magic behind the huge number of users (501023 etc.)?
  3. What is the difference between groups “appsupport-media-rw”, “appsupport-root”
  4. Which user, group and access rights do I need under “~/android_storage”

Seems to be a tough cookie to solve this…

EDIT:
Ich checked in Total Commander and under “/mnt/sdcard” there is “~/android_storage” mounted as it seems.
Also I don’t have issues with WhatsApp or other Android Apps.