Git with the Annex and LFS extensions is pre-installed in the JupyterLab Docker Container. You can also use the graphical integration of Git in JupyterLab.
Through the left sidebar, you can clone or manage a repository by clicking on the Git icon. This tool is directly dependent on the folder, which you can select via the file browser. To manage a repository, you must have previously selected the corresponding folder in the file browser.
Further information about Git can be obtained from here: https://git-scm.com/doc