Thank you. That code was for only “Message Box” page. To show in single message page you will need to override view-message-content.php template (instruction in https://www.shamimsplugins.com/docs/front-end-pm-pro/customization-front-end-pm-pro/change-templates/) then add your profile link with the names.
If you need my assistance to modify the template for your needs you can contact through https://www.shamimsplugins.com/hire/