This would be done on a from that is available to public to fill out.  So users wouldn't be authenticated.

I'm not sure where I should be placing the file and how to embed it into the form.

I have now figured out how to create a link and have it point to a file hosted on one of our publicly accessible sites, but I'm curious if the file can be uploaded to forms itself so user ends up downloading the pdf from the form portal itself.

<a href="https://www..........pdf" =="" download="Name_of_downloaded_file"><i><b>Hyperlink text</b></i></a>