When choosing the scroll to action, it means that the product will not be added to the cart, but that the page will automatically scroll up / down to an element inside the page.
The input box can accept a class name / path / ID.
(1) Open your product page
(2) Right click on the element you want to scroll to > select "inspect":
(3) Inside the bottom elements selector, hover on top of the element
(4) Right click the element > Copy > Copy selector
(5) Go back to the app tab and paste the selector inside
(6) Save your changes and test