fireworkswebsites

@hardikp Ypu will have to use a workaround for now:

In your functions.php file insert the following hooks:

add_action('woocommerce_checkout_process', 'afterpay_post');
function afterpay_post() {
    if(!session_id()) { session_start(); }
    if ($_POST['payment_method'] === 'afterpay') {
        $_SESSION['AFTERPAY'] = $_POST;
    }
}

add_action('woocommerce_checkout_update_order_meta', 'afterpay_delivery_date', 10, 1);
function afterpay_delivery_date($order_id) {
    if(!session_id()) { session_start(); }
    if(isset($_SESSION['AFTERPAY'])) {
        $data = $_SESSION['AFTERPAY'];
        foreach($data as $k=>$v) {
            $_POST[$k] = $v;
        }
        unset($_SESSION['AFTERPAY']);
    }
}

Basically this just saves your checkout’s form data from the $_POST object into a session variable. When Afterpay redirects back to your site, the 2nd hook takes that session and extracts the data and reassigns it to the $_POST object. The Delivery Date plugin handles the rest.