This app is available in sketch environment only, both in part and assembly context. When loaded for the first time, you will be asked to select a part file which contains at least one sketch block. The program will remember the selected part until you change it to another.

When a part with sketch blocks is selected, the app window will show how many blocks are available in that part. The list will be populated with all the blocks names from that part. When Insert button is pressed, the selected block will be copied to the active part and inserted in the active sketch. You are then able to select the location of insertion. 

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 can unload the plugin without uninstalling it by unchecking the "Loaded/Unloaded" check box associated with the plugin in the Autodesk® Inventor® Add-In Manager. You may have to restart Inventor to completely unload the application.

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, you can uninstall it from 'Control Panel/Programs and Features' (Windows 7/8.1/10), just as you would uninstall any other application from your system.

Currently the app doesn't work in an assembly sketch. It can import sketched block in the context of assembly, but at the part level sketch.