Install
Download latest deb file,
sudo dpkg -i plexmediaserver_0.9.8.18.290-11b7fdd_amd64.deb (replacing the last filename with the name of the package you downloaded)
Upgrading
Console will notify and provide a direct link. You may also just download latest from website,
sudo dpkg -i plexmediaserver_0.9.12.13.1464-4ccd2ca_amd64.deb (replacing the last filename with the name of the package you downloaded)
References
https://plexapp.zendesk.com/hc/en-us/articles/200288586-Installation
install avahi-utils first
Make sure mount directories allow pled access.
Version History - http://www.digital-digest.com/software/Plex_Media%29Center_history.html#55