In order to install plugin for Mopidy, i had to install git and run this command:

As all the documentation on Mopidy page is using sudo and python3 -m pip, i guess this may help.

README.rst

@@ -30,7 +30,8 @@ from the repository:
 .. code-block:: shell
 
     apt-get install libcairo2-dev libgirepository1.0-dev python-dev git
-    sudo python3 -m pip install Mopidy-MusicBox-Webclient
+    sudo python3 -m pip install git+https://dev.funkwhale.audio/funkwhale/mopidy.git
+
 
 .. note::