Using Amazon Firewall Manager in Regions that are disabled by default
To use Firewall Manager in a Region that's disabled by default, you must enable the Region for both the management account of your Amazon organization and the Firewall Manager default administrator account. For information about Regions that are disabled by default and how to enable them, see Managing Amazon Web Services Regions in the Amazon General Reference.
To enable a disabled Region
For both the Organizations management account and the Firewall Manager default administrator account, follow the guidance at Enabling a Region in the Amazon General Reference.