The interview went really well. I was interviewed by the PI of the lab and we just had a conversation. He spoke about his work and the aims of his lab. For the most part he did most of the talking. He asked me a few questions and I also asked him a few questions in return(need to show you are interested in the work being done). And he requested documents from me after the interview and within a week or two I got an offer. Every thing went pretty fast. A month later I started working.