Undefined property: stdClass::$authorization_endpoint

I’m new here and new to development, I’m trying to build my first authentication login for my PHP/Html app by following this tutorial https://developer.okta.com/blog/2018/07/09/five-minute-php-app-auth, when I try to visit the page at http://127.0.0.1:8080/ after building the login URL, I get a log in page with this error Notice : Undefined property: stdClass::$authorization_endpoint in C:\xampp\htdocs\okta\index.php on line 69. Would anyone be able to point me in the direction of what could be causing this error, I thought it might be to do with ports open on my apache server but I have tried all I can think off with no luck.

It was an incorrect url in the code for anyone wondering