You can also use your Google Drive or Dropbox download URLs with Webflow's form redirect URL to require a form submission before download.
Related solutions;
This directly accesses the CMS-stored file after form submit. In this approach, many file types such as PDFs will be displayed by most browsers, rather than downloaded.
This directly accesses the CMS-linked file after form submit. Here the file linked can be on a service like Dropbox or Google Drive, which use a mimetype that will force download rather than display.
You can host video on Dropbox.
Note there may be a delay before the file downloads enough to play.
You can host audio on Dropbox.
Note there may be a delay before the file downloads enough to play.