Demo: https://www.fmeextensions.com/product-attachments.html
Product Attachments extension by FME lets you upload pdf files to products in your e-store. You can upload tutorials, guides & other important files to product & CMS pages. You can upload the files to a separate download page created by this extension.
This Magento fIle upload extension supports multiple type of files like: videos, images, mp3, docs, pdf, ppt and many more.