It's not really the platform per se that they're evaluating.. I say don't worry too much about it. Main hantam kromo pun tak apa.

What they're looking for is your communication skills, how well you work with other team members and your reasoning skills.

My advice is.. during the group activity, be proactive and get involved....if your team mates elect you to be the group leader.. accept the responsibility but  always be open to suggestions from others. When it's your turn to present, make sure to give credit to everyone in the team... (at least the ones who deserve it). Do NOT HOG the limelight.. they hate that. Explain how you came up with the design as concisely as possible.. be honest about the problems you faced coming up with the design. Don't be too argumentative when the interviewers question your decisions.. think about what you're gonna say before you do and reply in a calm and rational manner.. else you'll just give them more license to 'hentam' you. 

SLB isn't really looking for the grad with the highest GPA. They want ppl who can work in a team, can communicate ideas and able to work under pressure without blowing his/her top off (trust me.. pressure comes from all directions.. supervisors.. colleagues.. clients).

Owh.. and never ever mention MONEY during the entire interview..