Permissions & Tokens error

My API settings are correct and it successfully connects, but when I move onto the next category for Permissions and Tokens there is a constant loading symbol.

Clicking 'Refresh User access token' brings up this error:

API Error Code: 191
API Error Description: The specified URL is not owned by the application
Error Message: Invalid redirect_uri: Given URL is not permitted by the application configuration.

Clicking 'Use a new facebook user for this setup' does nothing at all....

And so my posts are not posting to my facebook page.