In total there were 3 interviews. First one was a phone scanning. Second (including assignment) and third were with senior employees which have similar design background so that they can evaluate the skills and work process.
I was asked mostly, the top 10 general questions to probe me, why am I suitable for the position, what I like about doing that type of work, long term plans etc. If you google for interview questions you can prepare yourself mentally for what is coming.
I focused on honest discussion about my experience and why I want to work with design. The interviewing people were very friendly, so this made having a good discussion quite natural.
In my opinion talking about the assignment and describing the process behind the result had the more influence than all the questions. Furthermore, showing your personality and how you can fit into the culture is very important too.