Just tried to open the zip files with stuffit expander, on the Mac, and it says it's not recognised... Know next to nothing about Macs so it could be a user error.. but any help would be appreciated..
The 'zipping' was carried out on a Mac so you really shouldn't have any problems.
Is it possible that the download was interrupted? How large is the zipped file you have downloaded? If you click once on the file to highlight it and then tap the letter 'I' while simultaneously holding down the 'Apple-Command' Key (next to the space bar) an information window will open indicating the file size which should be 13.4 MB.
Edited to add: Is it the zipped .pdf you have downloaded, bushblade has posted two links in the original post, one is for a PC slideshow, the second one is for the .pdf, this one.