Hi,
You can make the phone number field required by just editing our template file for the listing form. You will have to edit the file under /wp-content/plugins/advanced-classifieds-and-directory-pro/public/partials/user/acadp-public-edit-listing-display.php
You just need to add the “required” attribute in the field elements you’ve mentioned.
But, instead of editing the above file directly, I would recommend writing an override. Kindly follow https://pluginsware.com/documentation/customizing-acadp-templates/ to write an ACADP template override.
Thanks