Very nice interviewer, they asked in detail about my cv and motivations. if there is time left in the end you get 1-2 brainteasers/ case studies. I only got one which was, how many petrol stations are there in Germany, without looking it up. Verbalise the thought process and give a number in the end, for example how many people live in my hometown, how many petrol stations are there and then take this number and apply it on the whole of Germany. I didn´t know the number of petrol stations (cause I dont own a car) so that led to me not getting the internship. Other examples of this case are how many pets are there in Germany etc. I prepared for more strategic cases, so not sure what skills that tests, but prepare for cases like this, that I didn´t know this apparently seemed like I didn´t prepare. But the interviewer was really nice and well prepared and made me feel safe.