Quoted from the site itself:
When I order my Universal Orlando® Preferred Annual Pass online using FLEXPAY, how will I receive it?
You can receive your tickets in one (1) of two (2) ways:
Electronic Pickup (Kiosk Pickup) - When you place an order online, the tickets can be available for pickup at one of the Electronic Ticketing Machines, or Kiosks, about 48 hours after you have completed your order. The Electronic Ticketing Machines are located at the front gate of both Universal Studios Florida & Islands of Adventure.
US Mail - When you place an order online, the tickets can be delivered to you via the US mail.
The tickets will be mailed about 48 hours after you have completed your order, and delivery will take approximately two (2) weeks. (NOTE: If you need your tickets sooner than that, please do not choose this delivery option. Either order online and choose to receive your tickets via Electronic Pickup (Kiosk Pickup), or wait until you come to the park and visit any ticket window at either park to set up the flexible payment option).
Hope this helps..
If I wanted to purchase Universal's FLEXPAY annual passes at the park, where would I go?
Simply visit any of the ticket booths at either park and you will be able to set up and use the tickets the same day.
When will I be charged?
Your credit card will be charged approximately the same day every month. For example, if the first payment is taken on January 10, approximately the 10th of every month you will be charged again.