[Plugin: WP-FB-comments] Help Setting Up Plugin – Keep getting URL error

Hello,
Seem to not understand something to get this plugin to work. I keep getting the same error:

{
“error”: {
“type”: “OAuthException”,
“message”: “Invalid redirect_uri: Given URL is not allowed by the Application configuration.”
}
}

I’ve the FB App ID but have tried the page id for personal page, site page but nothing.

So all I should have to do after putting in correct
Application id
API key
Application secret
is
Facebook Page id
such as “lawlessstreet” or “154022171288671” which is the page I am trying to add.
Thank you in advance for your help. Checked FAQ but nothing there helped.

https://www.ads-software.com/extend/plugins/wp-fb-comments/