I just tested the app successfully on my Nexus 9 with android 6/USB/OTG and purchased it.
Unfortonately then I upgraded to android 7.
Since then qDslrDashboard crashes, if I try to establish the USB-Connection.
Something must have changed for OTG with android 7.
My observations:
OTG Troubleshooter is no longer able to detect a connected OTG adapter.
Android itself is able to access an USB-Stick, connected to OTG.
An other Remote Control App is still able to connect and control my camera (DSLR Remote Control). But this app not even comes close to the abilities of qDslrDashboard. So it is not an alternative.
I would be very happy, if this Issue can be resolved.