This plugin is delivered with NopAdvance Core plugin on which this plugin is dependent. You need to install the plugin using the plugin installation guide provided here.

Once the plugin have been installed, you will see the plugin menu under NopAdvance > Plugins > Chat Widget in your nopCommerce admin menu, similar as displayed in the below image.

Click on Configure menu item from the Chat Widget plugin menu as displayed above and you will be re-directed to the plugin Configuration page.