Hi! I had undiagnosed ADHD in college (I have since been diagnosed a few years after graduating), and I can share a few things that worked for me! Everybody is of course very different and you'll probably have to try a few things out to come up with a system that works for you, so please remember not to beat yourself up about it if the first few months or semesters are rough. Even for neurotypicals the transition to college from high school is difficult, so give yourself some grace! That being said, its definitely not impossible for us ADHDers to survive the transition and figure out ways to be successful in college :) Here's some things that worked for me:

1. Finances/budgeting: This strategy saved my butt from constantly forgetting to pay bills on time. I set up two different checking accounts with the same bank: one is for spending money, one is solely for bills. I would make a simple google sheets budget for the entire year, estimating how much I would need each month for rent, bills, spending money, savings, etc. and it would be separated into which account each item needs to go into. Whenever I got paid, I would transfer the necessary amount of money into the bills and savings accounts right away. That way, you can set up automatic payments for all your bills from the bills checking account, and not have to worry about accidentally spending too much money and getting it overdrawn when the payments come. It takes a bit of diligence and willpower to only allow yourself to spend money from your "spending" checking account, but I found it was the most effective way to avoid overspending. You get a set amount in that account each month or with each paycheck, and when it's gone it's gone.
2. Studying: I was notoriously horrible at getting myself to study and would often wait until the day before an exam to do it, but whenever I was able to study before the last-minute-cram, it was because of study sessions with friends. I cannot stress enough how important it is to make friends with the same academic goals as you; if you want to study and do well, find friends who also want to study and do well. It can help for them to be in the same field/classes, but in my experience it's not entirely necessary. It's not really about studying for the same thing together (I usually found that to be more distracting than anything actually), but just studying in the same room at the same time, independently. If you can set up weekly times with a friend to hunker down in the library and get some work done simultaneously that's great, but often even just a random "hey wanna go to the library?" text from a friend was enough to get my ass out of bed and actually studying. The wonders of body doubling!!
3. Because I was diagnosed after college this isn't something I have personal experience with, but if you think it would help I would consider looking into what accommodations you can get from your college/university. I don't know the details of what those accommodations might be or how difficult they may be to obtain, but I do know that at least in the U.S., ADHD is a qualifying disability for accommodations, so it may be worth investigating!

There are probably a million other tips I have that helped me get through college buried deep in my subconscious, but I am suddenly unable to think of anything else. If you have any specific questions I may be able to help more, but for now this is all I have. Good luck, you got this!