The four Adobe Substance 3D apps(including Stager) are included at no additional cost in the Creative Cloud All Apps plans for Higher Education colleges and universities. Substance 3D Assets are not included in the Higher Education plan. K-12 institutions do not have access to this offer at this time.
When logging in with an institutional account that already gives access to creative cloud for my college (UCLA), the Substance apps only give "Buy" as an option, while the rest of the suite give "open" or "install" options. If you click "Buy" on the substance apps and complete a purchase, Adobe will force you to create a "personal" version of your same educational account and bill you for a regular plan. You then need to log out of that account and back into the institutional account to use other creative cloud apps.