This was originally created by KUDr, and posted on C&C Guild Forums.
The archive branch has the original contents from the reuploaded archive file.
There's a lot of information about RefPack on the Niotso Wiki, but it's essentially a compression format made by EA and used in many of its games.
Even newer EA games, like The Sims 4, are still using it in some of its files.
gibbed/Gibbed.RefPack seems to be a project with the same goal as this one, and is probably worth a look.
The original source code was supposed to be on http://mazanec1.netbox.cz/svn/big/, but that website seems to be down for many years now.
Some people did manage to download the source code before the website went down, and have reuploaded it.
The one here was found on a DerelictStudios Forums post, kindly reuploaded by Banshee on PPMSite (direct download).
This repository is simply a way of sharing that source code, with the intent of making it easier for others to find and utilize it.
I'm not the author of this project.
All credit goes to KUDr for creating this tool.