Transfer from the National Brussels airport:

Below the airport, you find a station: get the train to  “Gare centrale’/Centraal station”;
At the ‘Gare centrale’, nearby you find the metro (underground) ‘Gare centrale’,  there take the line 5, towards ERASME/ERASMUS, get off at the terminus.

Transfer from Gare du Midi/Zuid Station:

At  the station Gare du Midi/Brussel Zuid (TGV station, Thalys, … ) come down in the subway station, in the basement take the subway line 6, direction “Koning Boudewijn/Roi Baudouin” or lines 2 ” Simonis (Leopold II ) ” come down to the fourth stop: station Beekkant, (+-5 minutes), opposite, on the same platform, take the subway line 5, direction “Erasme/Erasmus”, till the terminus (+-14 minutes).

Transfer from Charleroi airport (Brussels South):

There is a shuttle between Charleroi airport and Brussels (Gare du Midi/Brussel Zuid/Midi Station), there you can take the metro to the campus Erasme.