Before the first interview, I had to conduct a situational judgment test, which is very easy and tests in a very simple manner, whether you will be a burden as an intern.
Then the process started with a 45 min. phone interview with HR. The questions were mainly related to my CV, past work experience, extracurricular activities and experience with teamwork, etc. No technical questions were asked.
This was about 2 weeks later followed up with a more or less technical Interview by one of the team heads. There were a lot of questions about my technical skills and exposure to Risk Management, but no particular hard questions (only a few about VaR, ES, comparison of the two Risk Measures.)
Again 2 weeks later I had a personal interview at their location in Berlin with two employees who again asked a lot about my CV and asked several technical questions. This part was fairly hard because it was mathematically quite rigorous. The questions were about modeling of financial markets, i.e. a bit of Black-Scholes model, how to solve it, assumptions, etc. Therefore I can highly advise preparing rigorously for this part of the interview process since without a background in physics or mathematics it might be fairly tough.