Hi,
For some reason on the mac the game crashes (for me at least) immediately after you try to save your character's look. I'm not sure if it's just me or something else entirely. Here's what the notification looks like: 
Yep, a noted bug - Mac doesn't want you to overwrite files, which is what's happening here.
Someone else did this to get around it:
I had this problem too but found a way to make it work: right click on
the game and choose show contents, then go to the file MacOS, click on
the thing called nwjs and your game will pop up along with another
window, but you should be able to save this time.