I think this is the latest version
You must be registered to see the links
Plugin should go in CM3D2\Sybaris\Plugins\UnityInjector. Hotkey to trigger the user interface appears to be F9.
As for the mods I don't know what they do or how safe they are. Old CM mbody mods used to replace the default body.
No idea what the plugin does though. It gives the master body facial expression? It allows you to change/edit mbody without overriding the model?
I've never played CM but I'm somewhat aware of its limitations.
I think I actually repurposed some of the mbody mods that came with a mananime distribution
With a standard LMMT BepInEx installation and without any ManAnime provided mbody mods installed the plugin appears to load just fine and the male edit menu also works. So I assume there is some other mod or plugin that is breaking your UI. Most likely another plugin. See what other non LMMT plugin you have installed and that will likely be the issue. I've seen this kind of issue before in COM3D2 when NPRshader was conflicting with some other western in house built plugin.