Mate origins:

Select two or more occurrences and activate the command. The components will be constrained together, by flush constraints between the component's origin planes.

Assembly and part occurrences can be selected. The first selected component will be the 'base' component. All next components are constrained to the base component.

Mate origins with offsets:

Activate the command. A toolbar will appear. One or more part/assembly occurrences can be selected. 

It is possible to enable/disable each of the plane constraints (XY, YZ, XZ). It is also possible to add an offset to each constraint. Like with Mate origins, all selected components will be constrained to the base component. The offset for next components is multiplied, so when changing the base offset, all offsets change. To do this check 'Multiply Offsets'.

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" checkbox 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.