There are a lot of files but I couldn't find anything that seems like it has the resources I need.
Each .zip.XXX is a piece of the whole source file directory. To successfully unzip any of the files you need to unzip ALL of the .zip.XXX files. This is called a "split archive" and it's ideal for maintaining the unzipped file structure which is important for a large collection of files that .blends depend on.
To successfully unzip split archives like this, ALL .zip.XXX's need to be fully downloaded and in the same directory. To ensure your downloads are in fact fully downloaded: HUMAN_source-files.001-009 should be 1 GB. HUMAN_source-files.010 should be 583 MB
Once you have all zips downloaded at their full size and they're in the same directory, I recommend using 7zip to unzip them properly, as shown here:
Additionally, here's a video tutorial for unzipping split archives with 7zip:
NOTE: Someone has confirmed that Winrar also works as does Keka for Mac users. More info on unzipping split archives on Windows and Mac.