Adding Bearer Authentication Header not authenticating user

I have followed your tutorial at https://wp-oauth.com/kb/step-by-step-using-bearer-token-authorization-for-wp-rest-api/ using PHP cURL on the plugin.

When making a request to a WP default POST/authentication required API end-point or a custom WP API end-point, it does not have the user as authenticated and returns 0 for a function like wp_get_current_user_id(), stating the user has not been authenticated.