The application creates a ribbon panel in the “Add-Ins” tab, which features 3 buttons arranged in a drop-down list:

•  TriangS3d - creates a 3D Solid
•  TriangSubdM - creates a SubDMesh
•  TriangPfM - creates a Polyface Mesh

The command-line commands with the same names are also available.
After a command is invoked, the applications ask the user to select a set of points. If TriangS3d is invoked, it will ask for a Z coordinate for the reference plane, which is needed to close the 3D solid. The reference plane will be parallel to the World XY plane.
After the selection, it creates a 3D polygonal representation of the set of points.
The created 3D object is useful for creating sections, toposurfaces, and calculating the volume of excavation, etc.

The installer that ran when you downloaded this app/plug-in from Autodesk App Store will start installing the app/plug-in. OR, simply double-click the downloaded installer to install the app/plugin.
You may need to restart the Autodesk product to activate the app/plug-in.
To uninstall this plug-in, exit the Autodesk product if you are currently running it, simply rerun the installer, and select the "Uninstall" button. OR, click Control Panel > Programs > Programs and Features (Windows 7/8.1/10) and uninstall as you would any other application from your system.

Some software packages include this functionality, such as Autodesk® Revit® and Autodesk® AutoCAD® Civil 3D®.

Source code and theoretical background are available on Kean Walmsley’s blog:

https://www.keanw.com/2009/07/triangulating-an-autocad-3d-solid-from-a-set-of-points-using-net.html.

Polyface Mesh is limited to 32,767 points – this is an Autodesk® AutoCAD® limitation. The Triangulation of SubDMesh and 3D solid is limited to 200,000 points due to performance and memory usage considerations.