We have had a couple other people with similar issue. The zip archives are fine and apparently the problem resides in Safari. Do one of the following:
1) Rename the file: delete ".html" from the filename. Should now have ".zip" at the end.
2) Re-download using a different browser.
1) Rename the file: delete ".html" from the filename. Should now have ".zip" at the end.
2) Re-download using a different browser.