Important thing is to be able to improve bid-ask by observing what the interviewers do.
hey, could u please tell me more about the final round at their office?
Depends on what position you are interviewing for, but for an internship, there is one HR and one technical interview. HR interview is straightforward, work on your CV and some "stories" and you will be fine. For the technical interview, you need to be proficient in probability and market making questions. You also need to be fast, certainly. There are these mental math tests too, but I assume you know these by now. Do your best and good luck!