Why do you want to work here?

2 problem solving questions - one of which i asked for clarification for and the interviewer struggled to clarify, and incorrectly told me what I was to do with the question. Then proceeded to ask questions whilst i was working the question out, and also seemed to get confused at the question. The second problem solving question i solved straight away with no issues, it was correct first time. I was told over the phone that I took too long to solve problems and that they wouldn't be continuing further with me. Interviewer did not take notes at any point during this interview, feel as if i may have been hindered by confusion regarding question.