First select product popup addon from left panel by editing with elementor.

Then then drag this element and select product which you want to show for pop up.

Then go to advanced tab and select position absolute . Then drag this element where you want to show this pop up.

Now you can go style tab to change default style for product popup.

Please have a look on video link to set up product pop up.

https://www.loom.com/share/42d19f5b865d4cc6bdff564517e42b5e