Jellyfin cannot access external hdd

i set up a jellyfin server in a docker container using the docker compose config from here, and am getting a permission error when trying setup my libraries. i have tried removing the user line from the .yml to run jellyfin as root, giving permissions to the user, root, and making the directory where the hdd is public, but can get nothing to work. i have also tried installing plex to see if jellyfin is the issue, but i cannot setup a library there either. any help would be appreciated.