OK I tried that as well as "input" and got 2 different error messages. I never saw anything about creating a user anywhere, what do I do now? Thanks for the help btw, learning slowly.
# sudo usermod -aG render jellyfin
sudo usermod -aG video jellyfin
sudo usermod -aG input jellyfin
usermod: group 'render' does not exist
usermod: user 'jellyfin' does not exist
usermod: user 'jellyfin' does not exist