Talked with PI for 45 min, very simple questions about experience and why I want to work at the lab. Offer came a month later, interviews seemed to be conducted on a lab on lab basis

I received an email to schedule an interview. I went into their lab where the group interview was conducted. It was a non-formal conversation between me and the group that worked there. They asked me about my resume, my plans after graduation, my availability to work during the semester, and if I had applied to other internships.