Thanks, Squid! Yeah, I've read that New Permissions tool is the solution for my issue. Ran it and after 5mins it's been fixed!
To fix the issue with the files created by docker containers like Radarr, Sonarr and Bazarr, in the settings of those containers set these permissions:
CHMOD for files 0666
CHMOD for folders 0777
And set those permissions.
I hope that this helps somebody with the same issue.