In order to enable RaaS function in the Review Engine, you will need to add this script in your agency settings section. 

Note: Adding this script will enable Reviews Engine sub account settings in place of the Reputation Menu Link and disable the Highlevel Review Management system.

    (function(d, s, id, accessKey) {
        var js, fjs = d.getElementsByTagName(s)[0];
        if (d.getElementById(id)) {return;}
        js = d.createElement(s); = id;
        js.dataset.accessKey = accessKey;
        js.src = ""+(new Date()).getTime();
        fjs.parentNode.insertBefore(js, fjs);
    }(document, 'script', 'ghl_unified_script', 'ENTER_YOUR_ACCESS_KEY_HERE'));

First go to the Custom JS Section in your agency settings:

Then paste the code mentioned above in the Custom JS section:

Make sure to replace the INSERT_ACCESS_KEY_HERE with the access key in your Embeddable App Link from here
(All the values after '=' in the link)