It’s been several months so I forget the exact issue, but at that point whatever the C# runtime was didn’t install cleanly without manually building a specific branch or somesuch, with no official package being available for FreeBSD.
Is Docker not an option? As far as I can tell, Docker is available on FreeBSD, and Jellyfin has a Docker image available, I've been using it for a few years at this point (on Linux, though).
