You need to submit the answers to the challenge in your application. I applied in late January, and in mid-February, a recruiter reached out to me for a Life Story interview. We just talked about, well, my life story, how I got into data science, some difficulties that I came across, my extracurriculars, etc. The interviewer was super nice and professional and I really enjoyed it. About a month later, I had my technical interview with two of their data scientists, who were again super nice. We spent the first part delving into a data science project that I have worked on, talking about design choices and such. Then the second part was about a certain scenario, and some of the questions were in the form of "how would you measure...". I thought there would be SQL other questions like that but there weren't any. I had no idea how the interview went and thought I had a good chance of getting rejected. But I guess it went well enough.