Hi QuetzalUE,
Welcome to Microsoft Community.
Is there any error or prompt when you add your school account?
Normally, the steps to add a school or work account are as follows:
If you're using the same PC for both personal and school or business work, you may want to add various accounts to your PC to make it easier for you to get to the files, apps, and information associated with each account. When you access work or school, you'll be connected to your organization's domain and have access to its resources.
To add another account to your PC:
- Select Start > Settings > Accounts > Access work or school.
- Next to Add a work or school account, select Connect.
- Enter that person's account info, select the account type, and then select Add.
Add or remove accounts on your PC - Microsoft Support
I think that the case that can not be added is that the school account may need to be added in the school network environment or domain environment, which also needs attention. (You need to check with school staff)
If you have any questions, feel free to leave us a message.
Best regards
Manson | Microsoft Community Support Specialist