Close a popup when you submit a Fluent Forms Conversational Form inside that popup.

close_ff_conversational.php

<?php
/**
 * Close a popup when you submit a Fluent Forms Conversational Form inside that popup.
 * 
 * Watches for a specific element (".ff_conv_app_4 .text-success") being added to the DOM.
 * When detected, waits 2 seconds and then closes Popup Maker popup #441 if available.
 *
 * @since 1.0.0
 *
 * @return void
 */
function close_ff_conversational()
{ ?>
	<script type="text/javascript">
		// Immediately Invoked Function Expression (IIFE) for scope isolation.
		(function() {
			// Define the selector for the target element.
			// NOTE: Change the number 4 to your Fluent Forms form ID.
			const targetSelector = ".ff_conv_app_4 .text-success";

			// Create a MutationObserver instance.
			// This observer will watch for changes in the DOM.
			const observer = new MutationObserver(function(mutationsList, observerInstance) {
				// Iterate over each mutation record.
				for (const mutation of mutationsList) {
					// Check if the mutation type is 'childList', meaning nodes were added or removed.
					if (mutation.type === 'childList' && mutation.addedNodes.length > 0) {
						// Iterate over the added nodes.
						for (const node of mutation.addedNodes) {
							// Check if the added node is an Element node (type 1).
							if (node.nodeType === 1) {
								// Check if the added node itself matches the target selector,
								// or if it contains an element that matches the target selector.
								if (node.matches(targetSelector) || node.querySelector(targetSelector)) {
									// Log a message to the console indicating the element was added.
									console.log(`Element '${targetSelector}' was added to the DOM.`);

									setTimeout(() => {
										// Check if PUM (Popup Maker) is defined before trying to use it.
										// This prevents errors if PUM is not loaded on the page.
										// NOTE: Change 441 to your popup ID.
										if (typeof PUM !== 'undefined' && PUM.close) {
											PUM.close(441);
											console.log("PUM.close(441) called.");
										} else {
											console.warn("PUM or PUM.close is not defined. Popup might not close.");
										}
									}, 2000); // Wait for 2 seconds then close the popup.

									// Disconnect the observer once the element is found
									// to prevent further unnecessary observations.
									observerInstance.disconnect();
									return; // Exit the function after finding the element.
								}
							}
						}
					}
				}
			});

			// Start observing the document body for childList changes,
			// including changes in its entire subtree.
			// This allows detection of elements added anywhere within the document.
			observer.observe(document.body, {
				childList: true, // Observe additions/removals of child nodes.
				subtree: true // Observe all descendants of the target node (document.body).
			});

			console.log(`MutationObserver set up to detect when '${targetSelector}' is added to the DOM.`);
		})();
	</script>
<?php }
add_action('wp_footer', 'close_ff_conversational', 500);

Demo https://share.wppopupmaker.com/X6u6YOkg