Via Studielink you can enrol for an education programme at an university. As the Biology Bachelor's programme in Nijmegen has a maximum of 200 students, keep in mind that you need to register before the 15th of January. Also, if you get offered a place be sure to accept it in Studielink. 
Every education programme can have complementary demands for the admission. You can enrol via a DigiD, or with your Studielink account. It is necessary to enrol for your education programme every year again.