Are you talking about your pass for the convention?
With almost every con, when you pre-register, buy your pass ahead of time, you still have to pick it up on site. Most cons will have two lines at registration, one line for pre-registration, and one line for on site registration, buy your pass on site. The good thing about pre-registering is that the line should technically be shorter and move much faster as your pass is already printed and the paper work is filled out, and all you need to do is show an ID to pick up your pass. A lot of cons also will open up the pre-reg line earlier than the on site registration.
But I am not sure how this specific con works. Does it say anywhere on thier website about when you purchase the pass if you have to pick it up?
I would still definitely pre-reg/buy your pass ahead of time, and worse case scenario, plan on standing in the pre-reg line.