For 'Zero dollar pricing' feature to work, domain admin has to turn on the feature from domain panel.
If the feature is turned on by domain, sellers on the domain will be able to upload products with zero dollar price & buyers on the domain will be able to place on order on those products.
Sellers will be able to manually add a product with $0 as price or bulk upload via a file. File can contain all or some products with $0 as price.
Seller has to explicitly enter the price as $0. Leaving it empty will not be treated the same as entering the value as zero.
Buyers will be able to add a product with $0 price to cart, checkout & place order.