To get to campus from the railway station (or downtown), you should take the tramway. Tickets must be bought before you board ; vending machines at all tram stops accept coins, and bank cards compatible with the French chip system. You can download a complete map of public transport in Montpellier here.
Take tramway line 1 in the direction "Mosson", and get off at the stop "Université des Sciences et des Lettres", which is a 5-minute walk from the meeting venue. You then walk north towards a roundabout with a distinctive red modern art sculpture beyond which you will find the entrance to campus.
Once through the gates, building 11 can be found among the first buildings on the left from the "Entrée principale" (see the campus map here below)