Good catch @josh.
I just tried @David_McNae’s mp3 file in Dropbox, and that appears to be working properly.
So I uploaded the file to dropbox’s public folder, and generated a link like this.
“Dropbox - Police Siren Sound Effect (1).mp3 - Simplify your life”
And I had to replace host name and url parameter to this to get the direct file download url.
That works beautifully.