Hi guys! MeTube author here. Glad you like the software!
I'll be happy to assist where I can. I've never used Unraid so I know nothing about it, so I'll only be able to help with things that have to do with MeTube itself.
@Alex.b, I'm not sure how you're setting the user/group ID in the template (where can I see the template?), but if I'm understanding it right, and it's via PUID/PGID environment variables, then those don't have any effect in this docker image. The uid/gid are set via the docker daemon, as documented in the README. How this is configured in Unraid I don't know... But there's got to be a way!
@Hawkins12, as I said I know nothing about Unraid but still these don't look right... In the mount section, I think you want to use /mnt/user/Downloads/MeTube/cookies.txt as the host path. And in the environment variable section, you'll probably want YTDL_OPTIONS as the key, and the JSON string {"cookiefile":"/cookies.txt"} as the value.