Thanks to https://www.itzgeek.com/how-tos/linux/ubuntu-how-tos/how-to-install-plex-media-server-on-ubuntu-18-04-ubuntu-16-04-linux-mint-19.html
Using Plex Repository
Import the Plex repository’s GPG key using the curl command.
curl https://downloads.plex.tv/plex-keys/PlexSign.key | sudo apt-key add -
Add the Plex repository to your system using the below command
echo "deb https://downloads.plex.tv/repo/deb public main" | sudo tee /etc/apt/sources.list.d/plexmediaserver.list
Now, update the apt index and install the latest version of the Plex Media Server.
sudo apt update sudo apt install -y plexmediaserver
Plex Media Server package places repository configuration in
/etc/apt/sources.list.d directory. Since we already have the
plexmediaserver.list in the repo directory, the installer may ask you below questions. Type Y and press enter.
Configuration file '/etc/apt/sources.list.d/plexmediaserver.list' ==> File on system created by you or by a script. ==> File also in package provided by package maintainer. What would you like to do about it ? Your options are: Y or I : install the package maintainer's version N or O : keep your currently-installed version D : show the differences between the versions Z : start a shell to examine the situation The default action is to keep your current version. *** plexmediaserver.list (Y/I/N/O/D/Z) [default=N] ? Y Installing new version of config file /etc/apt/sources.list.d/plexmediaserver.list ...