I am trying to add the instances to a target group. However, to add them I need to click on a button called "Add to registered" which looks like this:

However, when I am trying to add the instances to my target group I literally cannot find a button that says "Add to registered"

How do I register these instances to the target group that I am creating?
Moreover, I have already tried clicking on "Include as pending below" and then it displays this:
I still could not see the register target button.