I had similar probs when I bought Carrara5 from Eovia(pre-DAZ) during a special promotion. The price wasn't nearly as good as the present deal, though Eovia's servers were straining to  keep up with demand. When E-Frontier gave away Poser5, I had to wait in the download que for over two weeks. I am sure that DAZ's server capacity is also being sorely tested at the moment.
The bad part of this is that it seems everyone and their Grandmother is trying to D/L and take advantage of this deal before it expires. The good side is that this shows that there is a demand for Carrara and more users= more incentive for DAZ to push development for the next ver.