Unzip problem for Of The Blue Colour Of The Sky Extra Nice Edition download

I've downloaded the zip file a couple of times from the Database area but receive an error from during the unzipping process:

"End-of-central-directory signature not found.  Either this file is not
  a zipfile, or it constitutes one disk of a multi-part archive.  In the
  latter case the central directory and zipfile comment will be found on
  the last disk(s) of this archive."

I've tried using Mac's Archive Utility and StuffIt Expander to unzip the file. I can't find contact info on the site for technical help. Any ideas?