I have Yosemite and was having issues. I'm not positive if this is what did it for me but I got it to finally work after I downloaded a driver from FTDIchip's website directly:
http://www.ftdichip.com/Drivers/VCP.htm
If you scroll to "Mac OS X 10.9 and above" you'll see there is a special .dmg file for FTDIUSBSerialDriver_v2_3.dmg
v2_3 is not avail on the US Cutter site which has only v2_18
You can't see the driver installed as you would a printer. You need the sure cuts a lot software in order to interact with the cutter.
Also, I didn't realize on the SC series you had to select 'CURRENT' and hit enter from the cutter's menu screen after the data has been sent.
