Thanks Nastia,
Let me elaborate.
A. I am using this widget to add content on page. This is how widget is displayed on web page.

B. This is the interface of the widget where I need to enter the URL to make the pop up appear.

When the user clicks on “Subscribe button” as show in point A, Hustle’s pop-up should appear. Now as you can see that this button requires a URL to direct to, as shown in point B, the options you’re suggesting aren’t working.
Looking forward to your reply.