One question we get a lot is, "why can't I upload pdf documents (or .ai and .eps files) into the online design tool?"
That's a great question, and while it seems like a very reasonable request to be able to do so, the tool simply just does not support it.
The process of importing these formats is a complicated one and in order to keep the cost of our products reasonable, we chose not to pursue the development and licensing costs associated with allowing those formats to be imported. Our system does support vector graphics in the form of SVG, which was originally designed to be used in web applications such as ours. And it translates very well when producing a high resolution PDF for output. And any program that can create an AI or EPS file, can also create an SVG file.