Hi @odsadmin,
I went to your website and had to enable the X theme and Woo Checkout Editor as they were disabled. Then I went to Woocommerce settings and changed the payment method to cash on delivery to be able to go beyond the checkout page and see the result.
The Additional Info in question was in the page after the checkout as expected:

Then, I saw that there is an additional button labeled View Invoice:

Clicking that button, brought up a PDF file that does not include the additional info. I did a little bit of research and found out that, the PDF invoice button functionality is not part of Woocommerce and a feature which the WooCommerce Print Invoices/Packing Lists plugin provides.
Naturally, that plugin is not aware of the additional info. You need to contact the plugin developer and see if they will be willing to add that feature to their plugin.
Thank you.