Directions: There are about 4 entrances from the courtyard, so make sure you enter at Reuvensplaats 3 specifically. Once you've entered, there is an all-gender, wheelchair accessible bathroom on your left hand.
Comments: [unsure about the changing table situation - haven't had a chance to check] This is a University Building. I am unsure whether any lectures/workgroups are given here, but if there are, I think the groups may be a bit on the smaller side. I would not recommend saying you're here for a student-for-a-day day if you don't have a student ID. If someone you don't know approaches you, you could probably say you're supposed to meet a friend/sibling/kid/... there instead, but I don't think people will ask unless you look really lost.