No redirect URI error, in sandbox env

Hello,

I am attempting to use the RingCentral embeddable widget and can use assistance in setting the redirectURL. I've followed this document for configuring the app, in developers.ringcentral.com. Step 4 indicates to add a redirect URL in app settings. I tried setting the OAuth Redirect URL to the following:

https://apps.ringcentral.com/integration/ringcentral-embeddable/1.5.0/redirect.html

But to no avail. When attempting to log into the widget (embedded in a local Angular app), I receive "No redirect uri is registered for the client".

I attempted to pass in the redirectURL, but receive the same error message. Here is my embedded script:

<script>
  (function () {
    var rcs = document.createElement("script");
    rcs.src =
      "https://apps.ringcentral.com/integration/ringcentral-embeddable/1.5.0/adapter.js?clientId=<MyClientId>&appServer=https://platform.devtest.ringcentral.com&redirectUri=https://apps.ringcentral.com/integration/ringcentral-embeddable/1.5.0/redirect.html";
    var rcs0 = document.getElementsByTagName("script")[0];
    rcs0.parentNode.insertBefore(rcs, rcs0);
  })();
</script>

How do I go about setting the redirect URL?

Note: when using the non-versioned adapter (https://ringcentral.github.io/ringcentral-embeddable/adapter.js) and not passing in the clientId, I am able to login successfully.