Submit resume on jobs site. Researchers contact you on their own accord. Mostly behavioral questions, plus some questions about your experience and interest in the research. Usually you get the job on the spot. Very simple.
I applied through university. The process took 2 days. I interviewed at Columbia University (New York, NY) in Sept 2021
Interview
The interview was a 30 minute meeting over Zoom. One to two people sat in on the Zoom meeting. The interview was more similar to a casual chat, where the interviewers describe the job, ask a few behavioral interview questions, and then ask about availability.