Ok so you’re using docker, the drive is a USB disk?

I think you need to:

• create a mount point folder
• mount the drive in fstab so it’s available on boot
• create a dedicated user for Jellyfin to run as
• make sure the new user has read/write access to the folders with media (this may mean changing ownership, adding to a new or existing group)
• set the docker container to run as the new user
• add the mount point as a volume inside the docker container
• add the folders with media in Jellyfin