Follow the steps below to provide the necessary permissions to auto-add Azure Subscriptions under the same tenant for monitoring when they are created or added in the Azure portal.
1. Go to the Azure portal and navigate to Management groups.

3. Click + Select members from the Members tab. In the right pane, choose the application you have created. Click Select.
4. Your application's name will now be added to the Members field. Click Next.
5. In the Review + assign tab, confirm if the details are correct and then click Review + assign.
Once the required role is applied to the Management group level, it will be applied to all the descendant Subscriptions automatically. Also, if any new Subscriptions are added to the tenant, attach the Subscriptions to the respective management group.
The above steps can also be followed when a Subscription is not listed for monitoring in Site24x7.