They need to give you the special website that you can book on to take advantage of their room block rate. Their room block coordinator or sales consultant sent this to them within 2 weeks of their returning the room block paperwork. At the very least, they need to tell you their group number so you can book over the phone.
You could try calling DFTW Group Reservations at 407-827-6799 and asking for the [Bride's Last Name / Groom's Last Name] Wedding rate. (If it's two grooms or two brides, you may have to try both combinations of names.) If the block is already done, which it sounds like it is, they can book you over the phone.