Cannot unzip OS 1.31

Hi
I'm following MPC tutor's advice to upgrade (my OS is currently 1.13) to OS 1.31. I've downloaded the new software from https://www.akaipro.com/mpc500, and tried unzipping the mpc500.bin file from my downloads. Stuffit Expander throws up a dialog saying 'The Stuffit Engine was unable to determine the file format.'

Any ideas how to get 1.31 unzipped and installed? I'm on Mac OS Sierra

Thanks!

Dan

The 'bin' file is the OS, it doesn't need unzipping, don't do anything with this other than transfer to your CF card and install as per the instructions Akai give.