Hi,
Unfortunately, add to cart button didn't work within our VM Carousel in a proper way (modal box has refused to popup). So we didn't add that functionality to our VM Carousel Extension at all. It is also same in our DEMO as well. There is no "add to cart" button at all. Things might be changed in VM2.0.10 though, we should better try to implement it again with this new release. This is one of the most desirable functionality in our VM Carousel Extension though.
Flexible Support Team.