The other apps (probably sonarr/radarr/jellyseer?) are for downloading content, for watching what you already have jellyfin alone will do the job. The only other one you might want is an avahi client, so that on the local network you can connect with [pc’s name].local:8096 instead of 192.168.0.whatever:8096.
Usually for jellyfin alone its enough to install it (from apt, assuming you’re on a Debian based distro), make it auto start with sudo systemctl enable jellyfin, and then turn it on with sudo systemctl start jellyfin. That should be enough to see it running from your local network, although you might have to use your local ip if avahi isn’t on.
Anyway no pressure to jump back into troubleshooting this, just wanted to say it so you don’t feel like whatever programs youtube was recommending are mandatory.

Direct link, cuz the other one’s paywalled for me

Remotely as in from another computer on the same network, or from another network? Cuz connecting from another network will take some extra steps (usually forwarding a port on your router). The Linux communities on here are pretty receptive to questions if you’re stuck, too