How to acsess microsoft store on school computer

If this is a school computer, then school IT/admin must have put a restriction on it. No one, including Microsoft support, has the authority to help you bypass it.

It’s important to understand that Microsoft does not have the authority to manage individual users or devices within an organization. Each organization’s IT department is responsible for managing its own users and devices, following its own protocols and security policies. Microsoft’s role is to support the organization’s IT administrators by providing tools, not to bypass them or intervene directly.

In your case, you need to reach out to the school's IT department to do this if you have a legitimate reason to use the app you need. They are the admin user in this case.

If you are using a school computer, then the school has probably set limits to what you can use. Contact your school.