Create a class with a file attribute. Display it on your twig (generating something like that : /content/download/125/875/version/3/file/small.webm).
When I'm anonymous, I can't download the file (login required). If I'm connected I can download it.
I try to affect the rules content > all to anonymous: doesn't work. With full access like administrators: doesn't work.

The download is active only if I add this this in my site.ini :
[SiteAccessSettings]
AnonymousAccessList[]=content/download