Well, nobody else will know this, better place a link to your Site, to allow others to take a look. And always mention the OC Version and Theme you use in your Postings here, to eventually get some free assistance.
My Github OC Site: https://github.com/IP-CAM
5'000 + FREE OC Extensions, on the World's largest Github OC Repository Archive Site.
I believe you get access to them as a customer - only once you've bought the product do they appear in your customer account area.
There are various extensions that allow you to add PDFs to the product pages.
For quick, professional OpenCart support please email firstname.lastname@example.org