There are 3 interviews:
1- The first one with HR, where you just need to show your interest in Meltwater
2- Group interview: you will need to show to the recruiters that you are not afraid of improvising, critical thinking and talking in public
3- Final interview with the director, your future manager and 1 or 2 more people. This one is the most important, you will do some role plays, where you have to show your communication skills and problem solving. Advise: Be yourself, try to make it conversational.