As a freshmen in high school it really doesn't matter what type of lifting program you are on. Your focus should be on learning the movements correctly and building general strength, speed, and technique. *Understand that these are very general statements and that there are always multiple factors involved when creating a lifting program*
There are many questions that will play in to this decision. How solid is the schools' program? How much will working out with the team benefit you from the coaches' stand point? How much more, if at all, would your results improve with a Cressey program?
You have to look at both situations and determine which has a better return on investment. I am an absolutely huge advocate for Cressey and his work, but in all honesty, unless your schools' lifting program is just trash, it might benefit you more to get immersed with the team and train with them. This is coming from a strength and conditioning coach who runs his own facility, btw.
One last note: An athlete who performs a poorly designed strength and conditioning program with 100% effort every day almost always sees better results than an athlete who performs the best program ever with terrible effort.