Smart Library requires Unity 2020.3 or above.
Smart Library requires the Quick Search 3.0.0-preview package when used in Unity 2020.3. Newer versions of Unity ship the package and does not need to be added manually.
Go to the Unity Asset Store to get Smart Library!
After Smart Library has been imported, you can just open the window using the menu (Window > Smart Library) or the shortcut “Shift + L”.