Step 1: Go to 'Integrations' and click 'Marketing Emails' on the right.

Step 2: Click on connect button next to 'EmailOctopus'. 

Step 3: Log in to your EmailOctopus account, click on the top right username and navigate 'Integrations and API'.

Step 4: Select the 'Integration & API' tab and  Click on Create button.

Step 5: Click the Create a key button again to create your API key.

Step 6: Here is the generated API key, Now Copy the API key.

Step 7: Go back to your Sumopreneur account, and you will see a pop-up where you'll ask for Name, API Key.

Give a name to your integration. 

And Paste the copied API Key click the update button to connect the service.