Hello Hannah,
I understand the frustration you're experiencing. If you're unable to access the Microsoft Authenticator app, you should have the option to use a different authentication method. During setup, if you registered multiple authentication methods, you can choose an alternative method to receive the verification code.
However, if you're still unable to access your account even with the alternative method, it's best to contact your school's Technical Help Desk. They have the tools and access necessary to resolve this issue and get you back into your email quickly.
Please let me know if there's anything else I can assist you with.
Vukasin