Someone made a nice packages for debian based systems that work without systemd. Seems identical to official packages except it has been rebuilt for non-plex-supported init systems:
There are also tools to build your own packages if you want to download direct from plex to be extra safe.
Essentially the minimum glibc for Plex 1.15 and above is going to be 2.14.1. Debian Wheezy is 2.13.
Your options for minimum compatibility is to upgrade to Debian/Devuan Jessie or try and upgrade just your libc6 packages from Jessie. I’ve googled and found some people have successfully updated their libc6 using Debian Jessie’s packages.
Note, changing libc6 can be problematic. Make sure you have backups and make sure you know how to rescue your system if you intend to go down that route.
Plex 1.15 and above is going to need glibc 2.14.1. Debian Wheezy is 2.13
Your options for minimum compatibility is to upgrade to Debian/Devuan Jessie or try and upgrade just your libc6 packages from Jessie.
I spun up a wheezy VM to provide the steps to upgrade libc6 (glibc) from Devuan Jessie. Before you do this, make sure you have backups. I only tested this on a VM. Plex Media Server was able to start once I upgraded.
Instructions to add Jessie sources and upgrade libc6:
Add the Devuan Jessie apt repoistory to your apt sources.
Edit /etc/apt/sources.list and add the following two lines: