Showing error for Intent inside IntentFilter on Mainactivity.cs

Hi,

I need to open my app by clicking a url. For that I follow the following url instructions:
https://blog.falafel.com/xamarin-android-launch-app-browser/

When I add codes IntentFilter to Mainactivity showing errors. Following is the screenshot of the error:

Any additional thing to enable the Intent?

Thanks in advance