If you have a passport from a country that is not a member of the European Union, you will have to apply for a student visa before your departure for Italy. A visa is required only for programs longer than 3 months (90 days), so, typically for Fall and Spring semesters.
If you are from a country that is not a member of the European Union, you will need a student visa to enter Italy if your program is more than 3 months long. For some countries, a visa may be required for studies under 90 days. Obtaining a student visa when indicated is mandatory by Italian law and must be obtained before you arrive. Applying for a student visa is a completely separate process from applying to FUA-AUF.