At 11/18/2019 the MakeHuman team development comes with many plugins for MakeHuman software:
These are plugins related to MakeHuman. The MakeHuman side plugins are installed by placing the directory (for example "9_export_mhx2") in the "plugins" directory where you unzipped or installed MakeHuman. On linux this is usually /usr/share/makehuman/plugins. The Blender side plugins are installed in Blender, in the addons part of the user preferences.
See the official website.