Hey there! I am a fellow Mac pro user!
I have downloaded FH, and still do play it 'till this day.
I suggest perhaps downloading it off another computer and plopping it on a USB.
Another option.. What I suggest, is downloading Wineskin Winery (The Latest one if possible). After downloading, create a wrapper and load it together with Feral Heart. (After that, when you run FH. It will say some updaters are needed etc, press download! From there, it should work.
Good luck~