Loop Posts Outside of WordPress Installation

The error is related to a file called Requests.php, that is not a WordPress file. I don’t see an include or require for this file in your code.

Eventually you can add this before require, and check for the wp-load.php path

define( 'WP_USE_THEMES', false );

But, do this, will not solve the error, may you add the code where Request.php appears ?