In case the animation effect does not apply to your selected button, you need to enter the proper class of Add-to-cart button in the following box and then click Save.
Step 1.
Go to your website, and hover on the element you want to be triggered. Right-click and click on Inspect.
Step 2.
Select the element > Right-click > Copy > Copy selector
Step 3.
Finally, paste your result in the "Custom class for cart button" field in the app: