Board Thread:Help Desk/@comment-1250011-20131027161506/@comment-7697305-20131029015221

I believe the most recent server software can always be found at the bottom of the page here (though I don't know if that link would work with a Mac).

As for actually getting a server running on a Mac, these threads are about the most recent I can find: Hope this helps!
 * http://www.terrariaonline.com/threads/setting-up-server-on-mac.112539 (This one is unresolved, but you may want to follow it if you have an account on TO, as it seems to be closest to your problem.)
 * http://www.terrariaonline.com/threads/running-it-on-wine-macosx.114811 (This one's resolved, but I don't know how relevant it would be.)