Just downloaded the complete package from
http://www.subsim.com/radioroom/down...o=file&id=3975
and unzipped it with no problem.
Of course, you did notice that the file you downloaded is named
Dynamic Environment SH5 v 2.9.7z
and is a 7zip archive, and you did use 7zip to extract the files, didn't you?
Especially since the very first comment, which you refer to, tells you that it won't extract with WinZip?