These instructions refer to using comments within the creating order/quote page of ODB. Which can be found in:
admin → odb → create new quote/order.
You can add a comment by going to the shipping and payment information section and adding a comment into the box under the comments for customer heading.
This will save to the quote /order and add to any sent emails.
https://rixxo-hq.atlassian.net/wiki/spaces/ODBUSG/pages/2389573842/Products+in+ODB#Product-Comments