I applied online through my university's internship database. I got an e-mail directly from a research engineer like a week after saying I was on the top of his list and asking if I was still interested by the position.
He then mentioned they still had like a month to screen all applicants. So 4 weeks later he emailed me again asking if I could drop by for an interview.
Basically when I got there he started to explain what the project was and details about the job and the lab itself. So it was more like an informative interview, I said I'd take it and we were good.