Zanki is a completely free pre-made deck for USMLE step 1 with around 25,000 flashcards that you upload into Anki which is also free. Firecracker is not free, I believe its a minimum 100$ for 3 months. The benefit of these is that the flash cards are made for you and all you have to do is study them. I personally think, at least for first year, that you get a lot more out of making your own cards. This is because the professors write questions that come straight out of their powerpoint lectures. Zanki and Firecracker make their cards out of board material such as First Aid and Pathoma and as such they won't cover all the things that your profs will cover. If you decide you like using pre-made decks than check out
reddit.com/r/medicalschoolanki
I would get acclimated to using Anki. It is by far the best flashcard software out there and it is totally free. That being said, it is not perfect and there is a bit of a learning curve to properly and quickly making cards. Check out a few youtube videos on Anki tutorials and get the Image Occlusion add-on. It is super clutch for memorizing anatomy. I made my own flashcards out of lecture material during first year and it worked out for me. Starting first year already knowing how to use Anki will be really helpful.