It sounds like the Zumo 32U4 device is not being recognized by your Mac. If you have not already done so, can you try using a different USB cable (one you know is working)? Can you also run
dmesg | tail - 30 immediately after connecting the Zumo to your Mac and post the output results here?
With regards to not seeing the "Pololu A-Star 32U4" board entry in your Arduino IDE, did you restart the IDE after copying the "pololu" folder into the "hardware" folder of your Arduino IDE's sketchbook directory? The sketchbook directory can be found under File->Preferences of your Arduino IDE.