The library is located here: %ALLUSERSPROFILE%\Autodesk\RVT 2019\Libraries
If your office is using a different library of content in another location, your system may access that library by default. Contact your CAD Manager for more information.
To load families
At the top right of the dialog, under Preview, a thumbnail image of the family displays.
The family type is now available to place in the project. It displays in the appropriate category under Families in the Project Browser.