An Apple Developer Licence Agreement is required to be maintained in order to have any app available in the App Store. If your school app isn't appearing in the App Store, it's likely that your Apple Developer Licence Agreement is expired or awaiting approvals.
To check the status of your school's Apple Developer Licence Agreement, please log into your Developer Account. If there doesn't appear to be any outstanding issues or requirements in your account, please contact Digistorm Support so that our team can investigate for you.