I raced for 4 years in college and got my start through collegiate. It's going depend on what conference you're in (I raced in the NWCCC) and the schools you race against. I had teammates that raced ECCC and other more competitive conferences that would tell stories about racing against schools like Marian and that didn't match with my experience.
Number one point is that the community at collegiate racing is awesome. You race against and with the same people ~8 weeks in a row so you really get to know them and become good friends. My best friends I made in college were the guys I traveled to all the races with, shared uncomfortable sleeping arrangements in random people's houses and put off homework with to the point of staying up way past a reasonable hour once I got back. The only regret I have about collegiate racing was not doing more my first two years in school.
Regarding competition, if you end up racing A's, it's going to be like 1/2/3 race. There are the guys who are fit and know what they're doing and the guys who are still learning. Big skill divide because of the way the categories are combined. Nationals (2017) is still the hardest race I've ever done and I got dropped and rode most of it alone. Still was completely destroyed afterwards. Conference races usually have small fields. In the NWCCC we raced about 10-15 in the A's. It makes racing hard when you're in that small of a pack, and as I mentioned above about knowing people, the racing becomes almost negative when everyone knows everyone's strengths.
Unless you're going to a varsity school, there won't be tryout, it will more than likely just be you joining a club. Show up at a booth, get your name on the email list and go ride. Or get in touch beforehand with officers / other A riders and start networking before all that stuff.
Collegiate cycling has been the highlight of my cycling "career" and I'm more than willing to answer any questions you may have. If you don't want it to be public shoot me a pm and I can answer it there. I would also highly recommend shooting the school you think you will be attending a message on their socials and asking questions to them. They'll know better than anyone else. Maybe even get out for a ride with them on one of their club run if you're local.