Most of us leave our download links as xxxxxxxx.pdf and we put instructions (Right click to save target us).
What happens when some of us click on the hyperlink and the file is 5MB or even 10MB? The Internet browser normally doesn't respond till the download is complete.
Normally I leave my files as zip files and even an accidental click brings the user to the download pop up.
So leaving your product format as zip file is a better choice for users.
Hope this helps.