To follow this guide you will need:
The correct role: the Security Administrator, Conditional Access Administrator, or Global Administrator roles are needed to perform these steps.
Navigate to the Azure Active Directory blade in the Azure Active Directory admin center.
From the side menu, select Properties:
At the bottom of the page, select "Manage Security Defaults":
A side menu to "Enable Security Defaults" should appear with a single control to enable Security Defaults. Slide it over to Yes.