How can Helen provide free shipping for a small group of promotional products?
Remove all shipping options from the Google Merchant Center account
Add “Free Shipping” to the Shopping campaign promotional text
Set the default shipping for all products to a flat rate of 0.00 USD
Add a specific shipping_label to the promotional products, and then set the shipping cost for those products to “Free”
https://www.youtube.com/watch?v=gnxWgvcsdEU