If you are a regular user, you would probably rather want to download a tarball instead of obtaining the git repository. Look at the FpRoadmap to see available versions with links to their tarballs.

If you wish, you can clone the FLEXPART repository with

git clone https://www.flexpart.eu/gitmob/flexpart

In order to work with a single branch (here: dev) only, make a new dir, change into it and then say

git init
git remote add -t dev -f origin https://www.flexpart.eu/gitmob/flexpart
git checkout dev

For an introduction to git see

• ​https://git-scm.com/
  • ​Pro Git book (html version)