Do you still have your JKA disc? Since JKA isn't available on Linux, downloading via Steam is a hassle but it can be done via SteamCMD. Essentially all you need for OpenJK is the asset PK3s, so if you can load up your disc and pull the assets from there then that would make it much easier.
You can download OpenJK for 64bit linux at this link. If you need 32bit, this one.
You can make a new folder called Jedi Academy in your Documents folder, and create a Gamedata folder in that folder. Then extract the files from the OpenJK DMG to that new Gamedata folder. You also will probably need SDL2, which the process for getting that can vary across Linux versions. But try launching OpenJK before attempting to get SDL2 first.
The OpenJK team has a tutorial on setting all this up but it's literally the most barebones tutorial ever that it makes me sad. If you need to use SteamCMD, their tutorial lists the steam ID for JKA.
Hopefully that will get you started.
