As soon as you start the program pick your target block from the pop-up list then the desired layer name from the second popup list.

Besides this, there are two options, distribution by either Rows & Columns or Distance. 

After specifying the desired settings just hit the execute button to specify the first point and the second point in the drawing in a rectangular shape for the block distribution.

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.