Why can't Kentico authorize Facebook page access?

I created a test Facebook page for publishing surf conditions from https://www.swfd.org/ to https://www.facebook.com/swfdtest

However, attempts to authorize Facebook page access throw the error: Failed to authorize access to the Facebook page. Please make sure that the Facebook page URL is correct and you are an administrator of that page.

Changing the URL in the Facebook app dashboard throws this different error: { "error": { "message": "Can't Load URL: The domain of this URL isn't included in the app's domains. To be able to load this URL, add all domains and subdomains of your app to the App Domains field in your app settings.", "type": "OAuthException", "code": 191, "fbtrace_id": "BkDTF358Hwj" } }

Because of the latter error, I'm confident we're making a connection to the Facebook app, but not to the page. Any suggestions? The Facebook page URL is correct and I am an administrator of that page.