SC on Windows / Linux / MacOS

The official Jellyfin Media Player software or the Jellyfin MPV Shim client.

1. You can get Jellyfin Media Player from here:
https://github.com/jellyfin/jellyfin-media-player/releases

Install, open the app, enter SC's address, enter login details and you're done!

Note that the app uses MPV (built-in), which is why it can play all the video formats you throw at it with ease.

The other great option is:

2. Jellyfin MPV Shim client (arguably the better option overall!) - which can be obtain from here:
https://github.com/jellyfin/jellyfin-mpv-shim/blob/master/README.md

Jellyfin MPV Shim client lets you "cast" Jellyfin media instance(s) to your system of choice, acting as a cast device. It then plays any media through MPV player on your system. This gives you a more direct approach when playing any media on SC, as well as satisfaction without having to really install anything (if you opt for the portable version).

The release page on Github provides installers for Windows - a portable version is also available.
For Linux, you can find Jellyfin MPV Shim on Flatpak.
For MacOS, please read through the guide provided.