Sickrage bad gateway 502

Hello!
I'm a beginner in linux.
I have installed, Transmission and sickrage. I have a data pool with folder /media/12345/Openmediavault/Torrent containing folders downloads, watch, incomple.
I have reset the rights 777 for these folders with
chown -R root:users Torrent/
chmod -R 777 Torrent/
even tried chmod -R g+s Torrent/

when Sickrage tries to add the torrents via Transmission http://XXX.XXX.XXX.XXX:9091/Transmission, I always have after a few Mo downloaded error:permission denied.
When I do ls -l in downloads, there is nothing.

I also have tried blackhole add in watch directory but transmission-daemon seems to never watch this folder and never start download even if I activated the watch folder in the OMV administration
Tanks for your help

All right! Solved the problem by reading a thread concerning permissions.
my folders downloads, watch and incomplete were in /media/12345/OpenMediaVault/Torrent

the rights were 777 in Torrent and descending folders bit OpenMediaVault was Only 774, so no execute rights for others.

The execute right for others must be set from /media to ...downloads, watch and incomplete to let Transmission work.

I'm surprised because I did
adduser debian-transmission users
it did nothing and the solution above worked.
If it can help someone...