I emailed the PI to say that I was interested in her research and to ask if she had any spots available. She she yes and we corresponded a bit by email. Then I had an in-person 1:1 interview with her. I thought it went fairly well. She didn't ask anything too difficult, but she was new to the university (and the country) and didn't seem to understand the distinction between a research assistant and a graduate student. She kept saying things about me being in graduate school, which I am currently not. That made the whole experience a bit confusing.