GridStore Unlimited Customers have the option of unlimited backups for their Microsoft Entra ID services. This is configured via the Microsoft Entra ID Product in Redapp at https://app.redstor.com. If you don't already have this product installed you can do so by following the steps outlined here. The product may add as a trial, in which case you can go ahead an upgrade it to the premium version at no additional charge as a GridStore Unlimited Customer.
For MATs with shared tenancies, the backups should be configured at the MAT 'Partner' level in RedApp. Services used just by individual schools should be configured at school level.
The following Redstor Support articles provide guidance:
How to backup and recover Microsoft Entra ID