I have been using Anki for several years (mostly after I had already graduated from college) and have done relatively well in my courses. I am currently doing a DIY postbac at UC Davis taking only upper-division science courses and will be transitioning to a formal postbac in spring 2022. This opinion will be from a student who averaged a B- as an undergrad to now a student who averages an A- from extension courses.
Whether exams are based on lecture slides, textbooks, or both, I use Anki the same way. I focus mainly on topics that I could not explain to someone else with confidence. For example, when I first learned about neuronal action potentials, I broke down each part of the action potential into Anki cards. I made 1 flashcard for each of the phases so that I could better understand the reasoning behind each phase (i.e depolarization, repolarization, refractory periods, etc).
The questions I made were specific and the questions were concise/simple. For example, 1 of my flashcards for neuronal action potential was "what channels are involved in the depolarization phase?" Answer: "voltage-gated sodium channels." I took it 1 step further and explained why the answer was correct. It's one thing to remember that voltage-gated sodium channels are involved in depolarization, but it's another to explain that the opening of these channels enables sodium influx, which contributes to the rise in membrane potential.
If you are able to find decks that others have made for the same course, by all means, use them. However, I personally believe that spending time making your own cards will be more beneficial for you. You will understand the acronyms or pneumonics you made. The cards you made will focus on topics that you don't know. Making your own flashcards help reinforce the topics since you're "rewriting" the information again. These are just my opinions, so please take it with a grain of salt.
Anki flashcards are great, but you should also consider looking for practice questions/problem sets to bolster your understanding of the material. Anki alone will only get you so far.
I hope this helps. There are tons of information about studying with Anki on YouTube.