You can plan your trips by train/metro/tram/bus in Google Maps or 9292 alternatively. Nikhef can be reached from Schiphol Airport by train in about 30–40 minutes (you can use the journey planner of the main Dutch railway operator). The most convenient method of paying is to "check in" and "check out" at stations using a debit- or credit card (via contactless payment). It is also possible to purchase a rechargeable card at a ticket machine.
More details on the use of public transport in Amsterdam can be found here.
