Pre-filling – Order code

Hello.
First of all, I would like to thank you for the great work you did in creating the plugin. It is very useful!
I don’t have much knowledge of the PHP language, but I need help with one question: I’m using the WP Travel Engine plugin to make reservations. When the reservation is created, the plugin automatically assigns a Booking ID to the reservation ($booking->ID). I intend for this field to automatically appear in the “Order Code” field of Pago por RedSys. I’ve tried several ways and the field is always empty. Can you help me?
Thanks for all the help.