The interview process consisted of a problem solving test and a round of 2 interviews. If you succeeded in the first round, you would pass to a second one, where you would have 2 more interviews. The problem solving test was, in my opinion, very long. I would recommend you to be prepared for this and to practice so that your mind is ready at the time.
In terms of the interview, I would recommend you to be prepared for very general questions, and be able to make an estimation through logical thinking. I don't think it is possible to prepare much for these type of questions. My advice would be to be familiarized with business terms and problems and, when the question arrives, be prepared to apply it in a creative manner. It is also important that you have a framework when you answer your questions, and that you start from there. For the case I would also recommend you to take your time and not rush to answer. I think that the worst thing you can do is say an absurd thing.
Each interview followed the same structure: personal background - you have to provide a situation in which you have demonstrated leadership skills and drive achievement -, case, questions.