There is an official "Outlook" app from Microsoft in both the App Store (Apple devices) and the Google Play Store (Android devices). The app is free to install and is very easy to configure. The app will perform better with Office 365 than the default email apps installed on your device.
After installing the app, follow the instructions to link it to your school Office 365 account using the same credentials you use to log in to Office 365 online.
If the computer is still having issues, come see IT Support in the library or email support at: email@example.com