The zip file you downloaded should contain a package file and a zip file ending in _Script. Unzip both files into your Mods folder, but do not unzip the zip file ending in _Script -- that should end up in the Mods folder still zipped.
The package file can be placed into a subfolder, however the script file must be placed directly in the Mods folder.
Princemajik also covers the manual install process in a mod review on YouTube. Although this video is for the SimLotto mod, the same technique is used for this mod.