After installation, a new tab will be available. With a button to run the app. 

The app is a floating window with buttons.

Parent - select parent of each selected node, if available

Child - select select children of each selected node

Siblings - select all sibling nodes of each selected node

Leaf - select leaf nodes of each selected node. A leaf node is the lowest level of hierarchy; these nodes have actual geometry data. 

All Under - select all child nodes of current recursively (children of children of... etc) all the way down to the leaf nodes

The installer that ran when you downloaded this app/plug-in from the 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 10/11) and uninstall as you would any other application from your system.

For a really big model, it might take a while to select all leaf nodes of the root node. 

TODO - add cancelation