If you have a license for CS5 (Creative Suite 5) you can download it directly from Adobe here, toward the bottom of the page: Download and Installation Help | Download and Installation Help
Maybe your school's IT folks will have a license you can use?
Otherwise, it would be a 30 day trial, fully functional, but only for those 30 days.
As Nancy said, CC 2015 (Creative Cloud 2015) is a very different program from what your school uses (7-8 versions away from each other).