Go to notification list >> Edit Notification >> Click tab

The first field that you come across in the click tab is the CTA label and link. Turn it on to display your call to action in the notification.

You can further customize the CTA label. You can change the font and the style of the font. Choose your colour for the text field. Also, you can change the background colour through the CTA background colour option.

Set CTA label action once you've clicked it. You can add a custom URL, and it will be redirected to the URL once you've clicked the CTA label. Or else you can choose the open collector form to capture the data. Further, You can customize the collector where you can write the collector text & set the capture field.

Or else you can choose the None of the above options if you don't want any action to occur once you've clicked the CTA label.