I applied through my school's career center / job database. I originally applied for a TS position.
First step was a phone interview with a TS employee which was basically just asking why epic, going over my resume/experiences, and asking questions . It was relaxed. I felt like I rambled, but I made it through so I suppose it's not so bad.
Next step was a skills assessment, which is the 4 part test that other people have mentioned. Some people take it before the onsite, but some take it during the onsite interview phase. I completed it at home, proctored through webcam. They say they judge by time and accuracy, but I took a while ~3-ish hours? I have some programming experience and it wasn't too difficult (refresh on basics like operations on strings/char arrays). After that, I took a behavioral/personality test (Rembrandt Profile).
A week or two later, I was invited onsite to interview for both Technical Services and Reporting Engineer (HR added the latter probably based on skills assessment results?). They fly you out to Madison, reimburse your food expenses, and you can ask for an extra day to explore the city if you want. Fun campus, I wish the dungeons&dragons themed building had d20 decor though (but it was more literal instead).
There was a tour, interview/overview + case study for each position, and an interview with HR (Implementation / Project managers also have to give a presentation on any subject). I was caught off guard though because I expected an actual interview with a TS person / BID person, but instead it was an 'Overview' where it was 3 of us and 1 employee learning about the position with Q&A for 30 min. I don't know if it was seriously just a Q&A or if I was suppose to sell myself or something... After the overview was an individual case study, where they give you some documents and present a problem that may come up working in that position and you go about describing your thought process and answer to the problem, with the interviewer presenting followup questions and answering any questions you need clarified. After, I also had to complete a short verbal assessment (analogies, grammar, etc.). The last interview was with HR where they asked what you like/dislike about the company and the positions, my relative preference between the two positions, and salary expectations. About two weeks later I got a phone call saying it was a tough decision, but they're moving on with other candidates.