The Epic recruiter reaches out to you and invites you to apply. Then you submit a resume. After submitting a resume, they send you links to take a personality assessment, web proctored GRE-like test & programing test. Next, you speak with a Trainer/Project manager for a screening.
They say that you can't prepare for this exam, but you can!
To ace the programming portion, take Fundamentals of C# for free at Microsoft's virtual academy.
To pass their web-proctoered exam, get a GRE quantitative study book or look at practice problems. Also study "modus tollens and ponens" like problems; there are a lot of those on their assessment.
Unless, you are a super genius, I really wouldn't waste the energy and time applying; they seem to be just building a database of qualified candidates for use one day.
FYI, the web-proctored exam is a total violation of privacy of your computer and the place you choose to take the test.