Shopify
On Shopify you do not paste anything into your theme. You connect the store from the dashboard and Cabina configures itself — API key included.
Open Install
Go to Install in your Cabina dashboard and pick the Shopify tab.
Enter your domain
Type your store domain, for example mystore.myshopify.com.
Authorise
Click Connect and authorise the Cabina app to access your store.
No key to copy
The API key is configured automatically: there is nothing to copy or paste.
Turn on the app embed
In the theme editor, turn on the “Cabina” app embed and save.
The last step is the one everybody skips. Shopify app embeds start switched off. While it stays off, the store shows as installed in your dashboard and your customers see absolutely nothing — no error, no warning.
After that, the button appears on your product pages.
How you can tell it worked
Open a product page on your store: the Cabina button sits right below the buy block. If it is not there, it is almost always the app embed left switched off — re-check step five before anything else.
For the other cases see Troubleshooting.
Would you rather paste the tag yourself?
You can: the manual install works on Shopify too. You will have to generate the key and authorise the domain yourself, though — two steps the connection above does for you.