You apply online and describe your previous experience. They ask you to submit proof of the college or university that you're currently attending by taking a photo of your student ID. Once approved, you take subject tests in the subjects you wish to tutor and you get your results immediately after completion.
I applied online. The process took 5 days. I interviewed at Chegg in Sep 2020
Interview
I had to provide proof of ID to confirm I was the same person as the one who completed the writtena application, I had to explain who I was and a little about myself, why I wanted the job and what my background/previous experience was in tutoring, and then answer 10 conceptual maths questions.