How are you downloading it? If you right-click on this URL and choose Save As, it works for me (making sure to rename the file to a .docx extension; Internet Explorer may be detecting it as .zip instead, which is a known issue with Open XML files and web servers which don’t provide the proper MIME Content-Type headers.)
Edit: I got that URL by browsing to the .docx file on github, and saving the shortcut from the “View Raw” link.
