Either order to have them delivered, or order *in advance* to arrange for them to be picked up. There's a section on their website about picking them up that will give you all the relevant info.
If you want to save a couple extra bucks, sign up for mousesavers.com emails. They come on the 15th and contain a link to save just a couple more bucks off of UCT tickets...there's still time to sign up, if you can wait until the 15th to purchase!