If you want to contribute to the ELPA library (e.g. put your improvements or ports to other architectures (and so forth) in the official ELPA version) the ELPA git version is the best way to.
Note that, in the git repository you can find various development branches, recent changes, etc., which are still untested and thus not production ready! Feel free to use them already, however, a guarantee of the correctness of the code can not be provided.
To obtain ELPA sources from the git repository, please go to https://gitlab.mpcdf.mpg.de/elpa/elpa and clone from there.