Now I'm stuck at the "Request the authorization from the application" process. After I clicked that link, a new window pop up and logged in to Facebook, then it shows this error:
Does anyone know how to fix this error? Please help.
Publishing on Facebook documentation also warns not to the insecure URL under any circumstance. Perhaps Facebook doesn't even allow it and I see you have both URLs as the same. Also, please check out the Facebook documentation as prompted.
I had done the integration earlier with facebook. But now those pages are not opening because of some security updates done by Facebook.
I think you need to give the Terms and conditions, Private policy URLs in the respective fields which are mandatory, and you need to give permissions in the developers account page. And you need to add the products to your page.
And in the Advanced settings add the valid callback uri's. The following links may help you.