In July of 2019, Ubisoft joined the Blender Foundation where they committed to using Blender in their animation studio. That Ubisoft relationship has born further fruit with the recent release of Mixer, an add-on for Blender that adds multi-user support to the popular open source graphics application.
Ubisoft describe Mixer as:
Mixer synchronizes in real time the modifications done to the scene and the objects it contains. During a collaboration session, Mixer displays the position of other participants and highlights their selections.
The project is open source under the GPL v3 open source license, with the project hosted on GitLab and documented on ReadTheDocs. To get started with Mixer simply download the most recent release zip file and install it in the Blender Add-ons folder (this process is documented in the video below, for more detail).
While Mixer enables multiple users to remotely work on the same Blend file, be aware that currently there are some caveats with only a subset of your scene being perfectly synchronized between users. You can learn more about the Ubosoft Mixer add-on for Blender in the video below.