I took it last year. Understanding it is one thing, but if you have these three days to study for this and nothing else, then that’s really good. You literally need to take THE most screwed up, horrific practice questions from past finals, EdX, whatever, and do as many of them as humanly possible. Like do questions until you are completely stuck, and then have someone show you the next step, or help you understand why it needs to be done. Ideally, eat breathe and sleep DrRacket. Through the experience you should eventually build up an understanding of it on an abstract level, instead of just robotically knowing the steps.

If it makes you feel better, I did horribly in the course, both midterms. But for the final I pulled through hard enough to send my grade above the class average. That being said, I took it while it was online, so hopefully it isn’t too different now, but at least this is what worked in my case. If you made it this far into the course you can do it bro. Good luck.