First make sure to have the original package installed. More on how to install the original package here
Run the composer command to install the package:
composer require larabug/nova-larabug-tool
Register the tool inside the app/Providers/NovaServiceProvider.php file:
use Larabug\NovaLarabugTool\NovaLarabugTool;
...
public function tools()
{
return [
new NovaLarabugTool
];
}