The entry requirements can be found here (under “General Information” → “Admission”).
Note that the program is designed for students with an undergraduate degree in cognitive science. Other degrees are not automatically excluded but admission requires competencies of at least 80 CP of the reference program (B.Sc. Cognitive Science at TU Darmstadt), i.e. in the areas of basic computer science (at least 30 CP), foundations of cognitive science (psychology, movement science, cognitive science, neuroscience, or related disciplines) (at least 30 CP) and advanced courses in cognitive science: linguistics, philosophy, sports science, psychology (at least 20 CP).