This is what is intended to become version 2 of MPFB. MPFB2 is a complete rewrite of MPFB1 with an entirely different code structure, which is why it is in a separate git repository. For a list of new features, see the change log.
In order to get up and running quickly, see the quick start guide.
While most basic functionality (for example the importer) is implemented and working, it is still a work in progress. For more information see the current status page.
MPFB 2 should peacefully co-exist with MPFB 1, so there should be no problem with checking it out to see if it works for you.
Note that MPFB 2 requires a Blender version of at least 2.90.
The root of the documentation is available here. If you are unfamiliar with MPFB, you will want to read the introduction to what MPFB is. Otherwise, the installation instructions might be a good place to start.
The FAQ might be a good idea to skin through too.