I'm getting the same issue as swrtvrk. Also when I attempt:
apt-get install --no-install-recommends plexmediaserver-installer
I get Package 'plexmediaserver-installer:armhf' has no installation candidate
apt-get install --no-install-recommends plexmediaserver-installer
I get Package 'plexmediaserver-installer:armhf' has no installation candidate