I applied for the position in early August. A few weeks later I got an email requesting that I complete the Sphynx test (they didn't call it that but that's what it is actually called). Like others have said the test takes about 4 hours and someone is watching you while you take it, however, I didn't find it particularly hard in any of the sections. If you have good technical skills it isn't harder than any questions you'll get from Google or Amazon. After the test, I thought I wouldn't get an interview opportunity because it took a little over a month for HR to tell me that I passed the test. They eventually did call me and scheduled a flight for me to visit Wisconsin. The on-site interview was honestly super fun. The day started with an overview of the product, after which we had the opportunity to talk to an engineer one-on-one and ask whatever questions we had about the internship or company. There was a brief campus tour (we only saw about 3 buildings) and then lunch. After lunch, we presented to an engineer about something we've developed and the challenges, algorithms, frameworks, etc that went into the project and finished everything with an HR interview. I believe that the order that things happen is different for each candidate. Everyone at the company is super nice and outgoing, make sure to ask a LOT of questions because the will be answered. Another candidate and I had some extra time between the last interview and our flight so we got maps of the campus and did a little self-guided tour which was incredible, not to mention that about 10 employees stopped to talk to us and asked if had any questions (as I said, everyone was super nice).