After clicking on [Add Point Pairs] you select source and target points from the drawing by pointing

The Plugin works with one main dialog. From there you launch all functionalities

You can choose, whether you want to enter source and target points alternately or first all source points and then all target points.

As soon as you have selected two point pairs the application automatically calculates the transformation parameters. By checking and unchecking the various point pairs you can decide which point pairs lead to optimal results.

Click on [Select Objects]. Now select typical objects of AutoCAD® AutoCAD® to be transformed.

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

The file …\help\helmert.pdf contains a functional description of the application.