To make Promotional Popup appears on Cart Page only, you can follow these.
If code doesn’t work, you can comment below, message or email me.
#1. First, you need to enable Promotional Popup.
#2. Next, use this code to Custom CSS
div.sqs-popup-overlay {
display:none !important;
}
body#cart div.sqs-popup-overlay {
display:block !important;
}