How to publish a pdf file stored in Google Drive on a Google site?

I've published a Google Sites web page accessible to everyone by links to PDF files (presentations of my courses).
Unfortunately, anyone trying to download pdf files needs a special authorization from me. This is because the pdf files are stored in my Google Drive account.

I would like to allow anyone to download it without any special permission from me. I want to share these files with the whole world, I do not want to send it
share invitations around. Until now, I have not found anyway around that.
I could try inserting the file directly from the player option located in the sidebar of Google Sites, but that does not seem to work in a text box.
Creating a sub page is an option, but it sounds awkward.
The instructions I saw on the web seem obsolete.

I think that there is a simple solution that I neglect.
Thanks in advance!