This is the default experience with a webflow pop-up interaction
Pop-up with custom attribute.
The first step involves copy the script to the right.
This should be pasted into the bottom custom code section (before /body)
Add a custom attribute for 'scroll' to the button you wish to use for opening and closing the popup. Alternatively you can use "both" to use the same button.
Note: adding a custom attribute in Webflow, can be done under the Element Settings and in the custom attributes section add Name=scroll | Value=action without quotes (" ").