First stage consisted of two 1:1 interviews, two tests, and one written exercise. For the first interview they gave me a booklet and 10 minutes to prepare some thoughts on the given company and the market, then went through calculations and qualitative answers with my interviewer. The second interview was a pretty straight forward market sizing case together with some qualitative brainstorming. Both interviewers were really nice and asked some CV / competency questions as well. The tests were significantly harder than the online tests in terms of time, but I don't think you were expected to answer all questions. For the written exercise, you had to read through a 20 page booklet and had to write a report within 30 minutes. I didn't finish the report, but laid out a structure with all things I wanted to cover in the beginning, which seemed to be fine as I got invited to the second round interview two weeks later.
Second round consisted of two 1:1 interviews, one presentation, and one group exercise. The cases were more difficult than my first round interviews, especially since one of the partners was pretty tough to read and didn't provide any help. One interview was structured (booklet, similar to the first round), the other one unstructured - make sure to be quick and drive towards the solution yourself. For the presentation, I had to read through a massive booklet (60+ pages) and create some hand-written slides on whether the private equity client should buy a major cinema chain. Make sure to read only the material that is relevant because you will not be able to finish otherwise. The group exercise is pretty straight forward - you work on a case with 4 or 5 other interviewees and each one of you receives different data.
Overall the interview process was well organised, but pretty long compared to other firms.