For your MAT to be able to aggregate data from all their schools on their MAT MIS site, they will send you a data sharing request.
You'll need to have the School: Action: Data Sharing Request: Administer permission to access the page and confirm the request. Only the Head Teacher has this permission by default.
How will I know there's a request?
Your MAT will send you an email with details of the request. Click the link in the email, or go to School > Data > Data Sharing to respond to the request.
Approving a request
Click into the request and click Accept to confirm and share your school data with your MAT MIS site.
Once data sharing is approved, your school is not able to edit it.