There are limited facilities in the students dormitory of the University of Zadar, as well as local hostels. The price range for the accommodation is 120 to 200 HRK (15-30 Euro) per night. Local hotels offer rooms in the price range of 300-700 HRK (50-100 Euro) per night. Private apartments can be found in a similar price range per apartment and night, but offering space for several people, and thus maybe be cheaper for groups.
The students dormitory capacity is limited. The reservation will be handled on a first-come-first-serve basis. Please register as soon as possible, if you want to stay in the dorm.

Pictures and a 3D-walkthough of the University dorm can be found here:

Location of the University dorm:
Google maps

Youth hostel:
Availability and reservation site

Hotel Bastion
Hotel Falkensteiner
Hotel Kolovare
Hotel Porto
Hotel Villa Nico