Outdated documentation + Sample App

[eddiehou2]

I've been trying to build out my Workplace app with the official documentation (https://developers.facebook.com/docs/workplace/third-party-apps/development/#getting-access-token) and this sample app which the document references but constantly getting this 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": "AzucDX_SIhaLPQIskA-9MAi"
}
}

I've tried probably all the solutions on the searchable internet, including doing exactly what the error is asking. Anyone else running into the issue with recent 3rd party apps creation?