I don't mean to be discouraging, especially given your stated track record to date.
Just that at university you have large quantities of material thrust at you to to digest and that this subject contains more than most. You just don't get the time to achieve the level of familiarity and understanding that you probably managed in High School / College. That comes with later reflection and use (sometimes it takes years).
You should be able to get a good feel for it in the timescale, which will stand you in good stead in the future, certainly sufficient for good exam grades.
I am not arguing for or against ther summer course, I don't know enough about the american undergraduate system to advise on this. I am just pointing out that it constitutes a very important grounding and trying to help you get the best out of it.
go well