Cant install on Debian 12

[Host-in-the-Shell]

That's great. Just for reference and in case somebody else is still stuck even after all of this, then there seems to be a permissions issue with one of the core directories (although that shouldn't happen if you've installed using the installation script, but let's continue).

What I would try then is to uninstall jellyfin, delete every directory related to it (/var/lib/jellyfin, /var/log/jellyfin, /var/cache/jellyfin) with a command like

Code:

sudo rm -r /var/lib/jellyfin /var/log/jellyfin /var/cache/jellyfin

 
and reinstall with the script to see if that gets rid of the permissions issue.

All that said, I'm glad you were able to fix the problem. If anything, I also forgot to ask you for the output of 

Code:

sudo systemctl status jellyfin.service

so it's my fault as well for assuming you would know to check that. But hey, all's well that ends well.