Actually, it is: «
[The link](ftp://vm.musicbrainz.org/pub/musicbrainz-vm/musicbrainz-server-2016-12-20.ova.torrent)» – just for whatever reason Discourse doesn't transform ftp:// links into actual links(?), and I didn't realise until your comment.
Edit: I changed the allowed link URL schemes to include "ftp". ftp:// links should now work too, and the link in that post might eventually works as well. (I tried rebuilding its HTML, but that didn't seem to have an immediate effect.)