My VW CC Sport 2014 won't start.

My car has had problems starting up for about 6 months now off and on. The
first time it happened, I was out of town for a week so it wasn't being used for
that amount of time, so I didn't pay it much attention, and it hadn't given me
problems since.
But as of 2 weeks ago, it's started again. All the lights turn on when I get in
my car, but once I try to start it, everything practically shuts off and the lights
dim. I've had it jumped each time and it drives just fine after that.
I took it to autozone to check the battery and alternator. They passed all the
tests. No check engine light, nothing. It only has about 90k miles on it.