The process is very extensive and annoying.
They send you 4 not so straightforward tasks to solve in 90min and obviously you can only accomplish that if you already do a lot of this kind of tasks so you have everything fresh on your mind. You should prepare by doing lots of exercises at Codility and other platforms. Also they monitor everything when you are doing the tasks.
The next step was more like an interrogation, but only with the bad cop. The interviewer was kind of aggressive speaking, and made sure to make me totally uncomfortable. Saying that I copied the code (which I did not).
When I shared my screen they were very angry because I was looking in other direction to think.