How to add a full name to an OPENCART invoice?

Question

opencart

ocstore version 2.3
tried like this <?php echo $order['firstname']; ?> - Undefined index: firstname in
As far as I understand, something needs to be added to the controller.
By analogy with the link
I wanted to insert into the controller
$data['firstname'] = $order_info['firstname'];
But it turns out that such a line already exists!
I can't figure it out, please help!

Answer 1

If in the controller $data['firstname'] = $order_info['firstname'];, that is, a variable in the data array, then <?php echo $firstname; ?>