Night Agency interview questions

I had my first phone interview, which went well. Then, they asked me to come in for an interview to meet the person who would have been my boss. On my way there, while I was transferring trains at times square, I got a phone call from the lady who interviewed me over the phone asking if I would rather come in another time, because the manager was busy. My other option was to meet with his assistant. This was 30 minutes before the interview was supposed to begin! Attempting to show initiative, I came in and met with his assistant. She was nice, and the interview seemed to go very well. She told me at the end of the interview that I should reach out and ask to schedule a time with the person who I was supposed to meet with initially. When I did, I received a response almost immediately saying the position had been filled, so there was no need for me to come in! The entire situation seemed very fishy to me, and I found it unprofessional.

1st round - I met with a client services lead for 30-45 minutes in the office. She asked what I was studying in school and how it related to advertising, what I was interested in within the industry, and some basic behavioral questions on how I would approach teamwork situations + disagreeing with other people. 2nd round - I came back in to the office to work on a project to submit to the hiring manager. The project was relatively simple, though it seemed like I was doing a couple hours of free work for them. Within a couple days of submitting the project, the hiring manager offered me the internship.