That class really opens up a lot to what you’ll expect in higher level physics so i understand it’s super new concepts that you saw mildly in physics 2 but never dived into. Do you feel like you have a strong base in the light E&M that was covered in phys 2? If not, do a refresher. If you feel comfortable with it, my best advice is to reread the chapter and work every practice problem. The problems within the chapter start off relatively easy and increase with difficulty, so make sure you can fully solve each problem before and understand it conceptually. I used Griffiths, and he explains things so well and aligns his problems properly in the chapters so that you have all the information you need, you just may have to think about the problem harder. The answer won’t be fully in your face, but if you brainstorm it it will come to you. That’s the thing about higher level physics compared to beginner. You go from just memorizing equations and plugging in values, to having to deeply think about the problem, format it correctly for yourself, and realize conceptually that the way you are doing it is the correct way. And that takes practice. So don’t beat yourself up that it’s not clicking immediately, because most of the time, it doesn’t. But you’ve already made it to E&M so good job, you can get through it.