The application period for the winter term 2017/18 (starting mid-October) is April 15 to May 31, 2017.
Applications to this program are processed by the central Admissions Office.
Applicants with a non-German Bachelor's degree have to initially apply via uni-assist, a fee-based service appointed by Freie Universität to evaluate international educational credentials. Since only uni-assist approved applications will be considered by the Admissions Office, you should submit your application to uni-assist as early as possible and well before the above deadline.
For more information on the application mechanics see
Application with German degree (online)
Application with non-German degree (via uni-assist)
For general information on studying at Freie Universität see
Student Services Center | General Academic Advising