You receive the following message in Microsoft Defender for Endpoint on your Mac:

System Extension Blocked

The program "wdavdaemon" tried to load new system extension(s). If you want to enable these extensions, open Security & Privacy System Preferences.

Apple requires that all new system extensions being installed from third-party developers in macOS be manually allowed.

1) Click Open Security Preferences.

2) In the bottom left-hand corner, click the lock icon.

3) Authenticate using Touch ID or the username and password of an administrator on your Mac.

4) Click Details.

5) Check the box(es) next to "Microsoft Defender ATP.app". Then, click OK.

NOTE: The exact name of the app may vary.

6) In the bottom left-hand corner, click the lock icon to secure the System Preferences.

7) Close System Preferences.

Outcome

Microsoft Defender for Endpoint will function as expected on your Mac.