Are you starting a brand new file? In later Steps you're not able to change your last name. If that's not the issue, maybe you just need to click around a bit more on the name section to get the game to trigger the typing option.
I'm sorry. I'll have to ask the programmer is there's a reason the Mac keyboard wouldn't work. Could you try typing letters to see if anything gets added to the end of the name or if that doesn't work either?
