I am unable to install the KetronFT application after downloading it from the Ketron.it website.

I have my Keyspan Twin Serial to USB Adapter cable connecting my XD3 to my iMac with OS X. The driver was previously installed.

These are the steps I followed:
I located the download link for the KetronFT application for MAC OS software on the Ketron.it website.

I selected the link for MAC OS. It downloaded a file KetronFT 1.01.sit. to my computer. I expanded the file. The KetronFT application icon was now there and viewable.

I clicked on the icon and attempted to install it, but received the following message:
"You can not open the application because it is not supported on this system".

Anyone else have a problem with that file from the Ketron website for Mac OS?

Thank you,