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 Powershell integration, as some functionality is not available via the Graph API. See Powershell Integration for Microsoft 365 for additional details.
Navigate to the Integrations section
Switch to the appropriate tenant
Click Connect for Microsoft 365
Move to Employees & Departments
Tip: Here you can easily multi-select & ignore any unmanaged accounts
Enable Secure for the respective tenant
And you're done. Now go make sure your environments are Secure!