Nyaa is a torrent tracker with submissions, while the animetake and others use something like a script + user submission filehost/DDL/torrent.

I know there's a WP plugin (WP Trader) for making a quick torrent tracker WP site, not sure about DDL submissions, but AFAIK it can also be made in WP. Using ready scripts could be easier, but I think making custom scripts, or having someone make one will be more secured.