I think this is a problem Torsten. My phone is at Android 7.0 and would would think most people with Android phones have allowed the routine OS updates, so will be at 7 or higher. Are we expected to downgrade our phones to make it work? Is there a workaround of some sort? This may be a deal breaker for me.
the app is already available for download - so do a download, install it and check if the app starts.
if not - you can get your money back and the board can go to some one...