Printful is a little more complicated than most other platforms because there are two parts of the connection:
A connection to your Printful account, which is established by Airlock.
A connection to your Printful store, which is established by an API key that you obtain from Printful.
This complexity is compounded by the fact that Printful's UI makes you select Settings / API and then pick a store from a dropdown, rather than picking a store and then looking at its API keys.
The most common issue connecting OrbitKit to Printful is using the wrong API key. Make sure you have selected the correct store in Printful's API dropdown:
Remember, you have to navigate to this API page, then pick the correct the store.
If you aren't certain which store your Printful Venue is attached to, check the Status box:
This is a frequent cause of "not found" errors when adding a blueprint. If you try to add a blueprint using the URL from a wrong store (with a different API key), Printful gives us the message "not found".