I want to set up plex server, no windows.. any simple options?

My wife consumes whatever media I throw at our Plex server and I'd like to stick with it (The tv's + set top boxes/remote controls are all easy for her to use and stream Plex fine)

I'd grabbed an old work PC I replaced years ago, Windows 10, and tossed a Plex server on it and it's worked for a long time but recently despite being used for NOTHING but Plex, its bloated itself like most Windows machines and I found Cortana taking 90% CPU (despite being disabled via registry) and some updates failing over and over.

I'd like to replace it (the software) but really no idea where to start, even the most helpful sites are just "use your favorite Unix then install Plex" or "Here are 56 perfect versions of Unix to install for your Plex server"

Honestly I use it for nothing except Plex, is there something easy enough I could look at?