The International Mobility Office (IMO) is not responsible for settling students in accommodation but tries to do its best providing all the necessary orientation and information for all incoming students. 
Renting a room in an apartment, shared with other students looking for an extra flat mate to share bills, is the best solution and a less expensive option. 
Remember that finding lodgings in Lisbon can be difficult, especially if you are staying for less than a year. While seeking for permanent accommodation the best option for first nights is to stay at a Youth Hostel. Make sure you have a reservation.