As soon as you run the program you will be prompted with a dialog to add your desired inputs to draw the HVAC Taper.

There is also an image in the same dialog describing the way you should go with the inputs.

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 7/8.1/10/11) and uninstall as you would any other application from your system.

https://autolispprograms.wordpress.com/hvac-taper/