If you signed up for Gatsby by using our native Shopify app (https://apps.shopify.com/gatsby), then simply press the "Launch Campaign" button within your Gatsby brand portal.
If you signed up for Gatsby on our website, you can still install the script to your Shopify store. Here are the steps:
Go to the Installation page in Gatsby:
Click down in the black box to copy the script into your mouse.
Then head into Shopify >> Online Store >> Edit code
Paste your Gatsby script above the </body> tag
That's it, press Save.
If you're button is not showing up on your website, make sure you clicked the "Launch Campaign" button within the Gatsby Brand Portal.