Linux Babe published a tutorial about installing Plex Media Server on Ubuntu 20.04 LTS.
How to Install Plex Media Server on Ubuntu 20.04 LTS Server/Desktop
This tutorial shows you how to install Plex media server on Ubuntu 20.04 LTS server/desktop. Enable Plex repository and access external hard drive.
How to Install Plex Media Server on Ubuntu 20.04 LTS Server/Desktop