The overall interview, to me, consists of total of three rounds:
1) Phone screening/interview
2) Online assessment
3) On-site interview
Everything happened to me relatively fast; from first applying to getting an offer only took me exactly one month. HR responded my emails very quickly and were very nice and helpful along the entire process.
Applied at the beginning of December for software developer, heard back from the HR the next day about setting up for a phone interview, but for TS. The phone interview was just some basic behavioral questions and going over your resume. The interviewer (a TS employee) will answer any questions you have towards the company and job, go over the basic duties of the position you apply for and make sure you still want to continue in the applying process.
Two days later, received an email to take an online-proctored assessments. I was freaking out about this test because I heard it can be hard. And like the others say, you can't really prepare for this. I think as long as you have some background in coding (I did MATLAB in Freshman year and that was it), you should be fine. If not, read some basic pseudo code introduction and you should be able to pass this round. The assessments consists of a speed test on math, math, verbal, introduction of a new programming language and the actual programming part. Only the first section has a two-minute limit and the rest is based on your accuracy and speed. I would recommend spend no more than three hours and no, you wouldn't know your score at the end.
Two days after the assessment, I was invited to the on-site interview. They put me and a bunch of recruits in a very nice hotel, all expenses paid(including everything you eat during the trip!). Got there the day before my interview and had a dinner with some Epic employees, it was super relaxed and they'd answer all your questions.
My interview started around 10. There was a demo showing the software, a tour around a small portion of the huge campus of Epic, a casual meeting and Q&A with a TS, lunch, some more verbal test, a case study, and a wrap-up interview with HR. The schedule was really tight but nothing really technical. All the interview questions can be found here on Glassdoor so I won't repeat them. Just be really nice and proactive in your tone and you should be more than fine. And you don't need to wear suit and tie for this day, just business causal or a button-up shirt would be good. Epic hires about 250 fresh college grads per year and they are constantly expanding, so chances are you will be hired!