The Hireview interview was some basic STAR questions. Then the personal interview with HR, you have to walk them through your CV. I recommend that you shouldn't just read it out, but you should tell a story and what you learned from each exp. After that follows a simple case. You just had to solve some stuff on a balance sheet and answer some questions about how you would tackle a certain problem. The group stage is actually not about solving the case which is given to you. It's more about how you work in a group and are able to present yourself here. I recommend that you try to be active and take a lead, but not dominate the others in a conversation.