Ok. I got past the first issue i think. The documentation for mac is a bit off-- it doesnt specify that you need to put /dev infront of the disk.
I did `sudo dd if=~/Downloads/ubuntu-15.04-esdk-2016.3-headless-z7020.img of=/dev/disk2 bs=1m` and it worked.
NOW an new issue!
I boot up, and the CR10 light comes on steady, but the CR8 light blinks-- any ideas?