To connect your Caribou account with your Shiptheory account, login to Shiptheory and navigate to the Manage Carriers page from the menu menu. From here, click Enable next to Caribou and you will see a page similar to the below.
Copy and paste your Caribou API key that you can get from within your Caribou customer account here: https://my.wearecaribou.com/technical/api.
Click the blue Test Connection button to check your API Key is corrected and then save. You are now connected.