Dear Halie,
Good day! Thank you for posting to Microsoft Community. We are happy to help you.
Per the description shared, I would like to summarize your concern i.e., when you try to sign into the Office apps with your school account you get the prompt "Your account { insert account email} does not allow editing on Mac. To learn more, contact your admin about your Office Plan."
If my understanding is correct, I would like you to check whether you are having the license "The latest desktop version of Office" in the Office 365 Subscription provided by school.
Open a browser> Access this link: https://portal.office.com/account/?ref=MeControl > Enter your Office 365 account details provided by school> View Subscriptions> See whether the above mentioned license is present.
If the license is not present, it means you can use the Office 365 app in the web but not the desktop apps. If you want the desktop apps of Office, you need to contact the IT admin of the school to get the appropriate license. Reference: How do I find my Microsoft 365 admin?
If you have license and you are getting an error, please remove the Office apps previous activation license files and re-activate the Office apps. Reference: How to remove Office license files on a Mac (microsoft.com)
We look forward to your response. Thanks for your cooperation.
Sincerely,
Mia | Microsoft Community Moderator