When you submit your products to Google, they must provide the shipping service/charges that you offer. If you do not provide a shipping method Google will not allow Smart Shopping ads and you will receive errors.
Please note you can only send one shipping option in the Google Feed so if you have a standard and express option for products in your website you can only send one to Google not both.
The shipping costs that you submit to Google must match the shipping costs provided on your website so that if a customer clicks through from an ad, they will see the same shipping cost on your site. NB: If Google identifies a discrepancy between your website shipping costs and the shipping costs for Google Shopping ads, the costs submitted to Google needs to be greater. If you are unable to match exactly, Google recommends overestimating shipping costs submitted to Google.
In Omnivore you can set up:
- A default shipping option
- Shipping using Product Groups
- Standard, Express options
If you wish to offer location based charges you will need to set this up in the Google Merchant Centre (GMC). See Google article Set up delivery zones.
More information about shipping on Google.