How can I exclude a dynamic URL to show a popup created using ‘WordPress Popup’ plugin

Within the javascript file the developer calls a method when the page loads.

jQuery(window).load(po_selectiveLoad);

This methods calls another method.

function po_selectiveLoad() {       
    po_load_popover();
}

If you replace it with this

function po_selectiveLoad() {
        var urlString = new String(window.location.href);
        if (!urlString.match(/\/cart\//)) {
            po_load_popover();
        }
    }

Of course this is not good because you will need to modify the plugin files.

I am not sure if the developer has provided the option of preventing a pop up based on a phrase or word contained within the url, i installed the plugin and did not see an option.

It may be a feature of the plugin the developer will implement at a later date or you can ask. Hope this helps.