While Microsoft is pushing the and PowerShell for modern management, ADUC remains the preferred tool for many admins due to its speed, familiarity, and the ease with which you can navigate nested OUs.
In the past, you had to download an installer from Microsoft’s website. Now, RSAT is an "Optional Feature" built directly into the OS. For Windows 11: Click and go to Settings . Select Apps from the sidebar, then click Optional features .
Restart the Windows Update service and try the installation again. (Don't forget to change it back to afterward). ADUC is missing "Advanced Features"
If this is your first time opening it after installation, you might see a red "X" or an error saying the domain could not be found.