How to set up a counter for the number of goods in VirtueMart?

Question

Joomla

At the checkout stage, display the information "Minimum total order quantity - 20 liters" in the shopping cart.
How to make the report start immediately with the number 20, and not from 1, as by default?
And another question: how to add a field to the order page with a message that the minimum order is 20l?
Thanks in advance!