https://account.plex.tv/claim

https://pimylifeup.com/raspberry-pi-plex-server/

sudo apt-get install apt-transport-https
curl https://downloads.plex.tv/plex-keys/PlexSign.key | sudo apt-key add -
echo deb https://downloads.plex.tv/repo/deb public main | sudo tee /etc/apt/sources.list.d/plexmediaserver.list
sudo apt-get update
sudo apt install plexmediaserver