Aria here, I'm on the Social Care team at Shopify. :)
You need to have shipping rates set up on your store, even if they are free. If everything is free shipping, it's actually pretty simple to set up. You'd go to Settings > Shipping in your admin then:
These images are taken from my test store!
You will need to do the same thing for every shipping zone you have set up. In most cases, people have a zone for their home country and a worldwide zone. Yours may be different.
You can find more information on setting up shipping rates in this guide.
I hope this is helpful!
Social Care Guru