Just unboxed an MKR1000 for Christmas, connected it to my Mac (running Mac OS X Sierra) with a USB cable (I’ve used both the one that came in the box, and another) but the simple blink sketch doesn’t work.
Very underwhelmed that there aren’t aren’t instructions when you buy the MKR1000 bundle, and connecting it doesn’t work.
Attached a screenshot of what I see. Any help appreciated!
Not a mac (spit) user but here goes.
Have you tried the "quickly double tap" the reset button.
This puts the MKR in bootloader mode and on another com port (translate that to mac speak)
Also be aware that a lot of issues surround USB 3.0 ports so if that's all you have then it is preferable to use a powered USB 2.0 hub between the USB 3.0 port and the Arduino.
Take your time and read some of the other posts in this section as there are a lot of useful tips in getting your MKR up and running.
I presume you have been here and followed the advice shown.
There are a few more links on that page too worth looking at.