When you travel from Schiphol (Amsterdam), you can best take the train. During the day, every 30 minutes a train departs from platform 1-2 at Schiphol. Sometimes a connection directly to Groningen; sometimes to Leeuwarden, in which case you have to change in Zwolle (same platform). Check details at the Dutch railways: https://www.ns.nl/en.

From the train station it’s a walk to the conference venue of 10 minutes – by taxi also 10 minutes.