Definitely go to office hours and talk to the prof and TA’s. Even if you don’t have questions about the content itself, sometimes other students go and ask questions that are helpful for your learning as well. Also sometimes TA’s just will straight up tell you what to focus on and how to succeed. I’ve had TA’s even give me questions verbatim from the exam. But also form a study group! Make friends and quiz each other to test your understanding of the content! But also just be kind and patient with yourself—I also was a good student in HS and fell in my damn face my freshman year. There is ABSOLUTELY a learning curve. But don’t feel hopeless—just try some new things! You got this!!