Try logging into your school and see if the history provides the EIN number there. You may also call the school and ask.
However, you are not required to enter EIN into TurboTax if the school is not required to send a 1098-T to you. Starting in 2016, this is an exception. The program will ask you 1098-T questions and, once you indicate you don't have the form 1098-T and qualify for this exception, TurboTax will only ask for your school's address.