DMG or Disk iMaGe is the default image format file for MAC OS to distribute programs, much like ISO is for windows. Mac Os is different than windows, it doesn't have exe, and rar, etc.
Did you follow
exactly the steps as described in the original post? When you unpack the ZIp file you downloaded what was inside? Was it only a dmg file or maybe... other files too?
Describe exactly the steps you did, that will help understand the problem, but I have a feeling you didn't follow the steps as
@Jimmie has posted.
Also, this torrent has been downloaded by almost 1800 people. You think if there was something that wrong, they would not have reported it?