There is a long take-home assessment before moving forward. It composes a series of different actions and it is just very tiring to complete and not a great assessment or reflection of anyone's ability.
I applied through a recruiter. The process took 4 weeks. I interviewed at Optiver (Amsterdam)
Interview
First a HR interview, after that you have a Math test with a mix of simple and medium hard questions. After that you have a numeric sequence test. This test was the hardest of the bunch. If you prepare them well, this should be easily doable. Overall a good experience