The files are a split archive so, as mentioned above, you need to download all of them and open them using something that can handle 7zip archives.
7zip appears to have a Mac version available here: https://www.7-zip.org/download.html – By choosing the 001 file to unarchive 7zip should automagically detect the rest of the files in the archive set and unarchive the lot of them. (As shown here, but this example shows Windows… https://cgcookie.com/lesson/intro-to-sculpting-the-human-head)
I hope this or previous answers help!
