"To share a campus" means that two or more different organizations or groups of people use the same location or property for their educational purposes or activities. Full definition
They typically share a campus with a comprehensive high school, so students can access a broader range of academic and extracurricular options. (grandcanyoninstitute.org)
It's become so successful the program expanded to two public schools sharing their campus. (thebronxchronicle.com)
Middle school boys and girls here share a campus. (edutopia.org)