hi! i'm having the same issue, also on el capitan. from what i'm reading here, i think the itch app is just incompatible with our dinosaur operating system. when i type the command in terminal, i get the 112 error.
I suspect you're right. I did try and find out what mac OSs are supported by the itch app but didn't find any solid information, would be good if this was made clear when downloading.
