Your M365 Secure journey begins by integrating M365 for the customer.
If you are an existing customer upon the Launch of Secure, you will need to re-authenticate your M365 integrations to accept new permissions.
Secure requires Exchange Online integration, as some functionality is not available via the Graph API. See for additional details.
Navigate to the Integrations section
Switch to the appropriate tenant
Connect to M365
Click Connect for Microsoft 365
Employees and Departments
Move to Employees & Departments
Enable Secure for the respective tenant
And you're done. Now go make sure your environments are Secure!