To block unsanctioned cloud apps on Windows 10 endpoints with Microsoft Defender for Endpoint and Microsoft Defender for Cloud Apps (formerly Cloud App Security), you must enable and configure the product integration on both sides. First, in Microsoft Defender Security Center # Settings # Advanced features , turn on the Microsoft Defender for Cloud Apps integration (and ensure network protection prerequisites are met). This allows Defender for Endpoint to receive the unsanctioned app list and enforce endpoint-based blocking when users on CLIENT1 attempt to access those apps via the browser or client.
Second, in Defender for Cloud Apps # Settings # Cloud Discovery , configure the Microsoft Defender for Endpoint integration and enable Block unsanctioned apps . In Cloud Discovery, apps are discovered, assessed, and can be tagged as Unsanctioned . Once the MDE integration is enabled, that tag is exported to endpoints, which then enforce blocking based on the tenant's app catalog and policies.
Options A (Onboarding settings) are for enrolling devices and do not control app blocking behavior. B (Anomaly detection policies) govern behavioral detections (e.g., impossible travel, anonymous IP) and are unrelated to endpoint enforcement of app access. Therefore, the two configurations you must modify to meet the require ment "block unsanctioned apps on Windows 10 computers by using Microsoft Defender for Endpoint" are C. Advanced features in Microsoft Defender Security Center and D. Cloud Discovery settings in Cloud App Security .