If you're selling on Google Shopping and using PrettyDamnQuick's checkout, you'll need to set your shipping rates manually in the Google Merchant Center.
Here's how:
In your Shopify account, under Sales channels > select Google
In the Google sales channel, select Settings
3. Under Settings, in Product feed settings, next to Shipping settings, click Manage
4. Make sure Manually set up shipping settings in Google Merchant Center is selected, and click Save.
After you change your shipping settings in your Google channel, you can set up your shipping rates manually in Google Merchant Center.
And that's it, you're all set!