i don't know the new versions of cubase but...
switch everything off, no... wait wait wait, i haven't finished yet...
when everything is off, plug up AUDIO 6, power up and then go to the apple icon in the top left of the finder window.
click about this mac
and then click more info
then click on system report (you might not see this bit and the next page opens anyway)
then click on the hardware column please hit USB
can you see the AUDIO 6 listed on the right?