Musicbox extention not visible in web gui

Hello!

I have gotten around to installing a mopidy once again with a fresh ubuntu 18.04.4 on raspberry pi 4 following the exact instructions indicated, as you listed above.

I then installed musicbox and soundcloud as indicated in their respective pages.

Any mopidy command, however, brings up the following:
ERROR: Mopidy requires Python 2.7, but found 3.6.9.

I have tried what was indicated in these pages, but to no avail

Any idea at all what can be done here? Any advice would be much appreciated. Thanks!