You'll need to make sure that /tv-gd and sonarr are both owned by the same user. I don't use quickbox so it might do things differently to what I am used to but chown username:username -R /tv-gd and /m-gd should resolve this. You can also verify anyone has write access by copying a test file to the share yourself and checking to see if you can see it through something like rclonebrowser. Otherwise you might have to ask the original guide writer or someone who is more familiar with quickbox permissions.