The main thing to keep in mind with this workflow is that "ordinary" users should never commit changes to master. All changes to the "local" master branch should come about by pull changes from the shared repository. If you inadvertently commit to master instead of to a feature branch, create the branch with "git branch <branchname>" and then reset the master branch to match the remote master branch (first making sure you are ON the master branch) with "git reset --hard origin/master". (This assume "origin" points to the remote repository.) Then checkout the branch you want to continue work on with "git checkout <branchname>".
I came to this part of the documentation because I wanted a definition of what the "site group" part of the GUI was referring to. It seems roughly defined here, but it might make sense to reference the wording in the GUI.