After applying they send you a huge questionnaire to fill out. They ask questions about your high school performance (english, math, leadership) regardless of the seniority of the position. My responses tended toward 20-30 pages. After that, there's an aptitude/behavioral GIA test which is basically quick reaction minor calculations, object rotations in your head, minor logic. It's pretty easy, and you only have to do it once a year.
Next, you're given a skills assessment on the horribly buggy DevSkiller website. I've had two interviews that used DevSkiller (both Canonical) and encountered errors both times. DON'T use the in-browser code editors as they take about 15 seconds to run your code and I've had the website throw an error and refuse to launch the fancier browser editor. You're much better off using your own code editor and the git submission system. Be forewarned that the practice problem still counts against your total time due to a bug in the system. The problems were your standard medium difficulty leetcode problems, but fighting the bugs in the DevSkiller website cut into valuable debugging time.
Despite having numerous advanced degrees and extensive experience, I didn't make it to the next stage of the interview process for a low level position. I never got to speak to an actual interviewer as their semi-automated evaluation systems blocked progression.
Frankly, given the massive amount of work required to apply, answer the questionnaires, complete the GIA, complete the technical assessments, I'm not sure I would ever bother applying again.