Quoted from m4tt:Big thanks to spandol for helping work through the Mac update process, with the help of thekaiser82 's comment of using the terminal. We found that Finder wasn't actually showing the hidden file so using the terminal is the way to go. You won't need it for the next update though, just this one.
The instructions on the website have been updated with the terminal command to use: https://www.spookypinball.com/game-support/hwn-um-update-process/
Thanks for all the positive comments and bug reports that have been sent through.
As a Mac guy, THANK YOU for this! I was able to update my game tonight without needing to ask someone to send me their thumb drive in the mail (btw... thanks, @mudflaps!). I played just one game, and I still suck (14K), but I can already tell that this is a nice step up from 1.09.
A tip to other Mac users who are using the steps on the website: make sure to include a space between the word "clean" and the "/Volumes/USBname" part. I didn't notice that at first and got the error message I'd grown so accustomed to when I plugged the thumb drive into the game. Once I realized my mistake, it worked like a charm.