Installing Plex server on headless Raspberry Pi

# update and upgrade
sudo apt-get update
sudo apt-get upgrade

# add plex repo
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

# install plex server
sudo apt-get update
sudo apt install plexmediaserver

Go to Your_Pi_IP_Address:32400/web on your browser to continue setup.