Including user data in “new user notification email”

I’m not sure how WooCommerce adds these fields, but I suspect it uses add_user_meta after the user_register form or something.
Try and catch it this way instead:

if ( isset( $_POST['first_name'] ) ) {
    $first_name = $_POST['first_name'];
}

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)