three-round interview with a very long processing time, you should be expecting waiting for up to 2 months to get the final deal (either hired or not) Be prepared that the interviewer could be more than just the hiring manager or your direct boss who is looking for filling a position, it could be a group of their colleges from other departments as well. They would add questions from the outside angle to see how you would react to it.

initial communication, planning, two rounds interviews