To use any of the above modules, you need to connect your MailerLite account to Integromat. If you do not have a MailerLite account yet, you can create one at Mailerlite.com.
To connect your MailerLite account to Integromat, follow the general instructions Connecting to services. When creating a scenario, you will be asked to provide an API key. To get your API key, login to your MailerLite account (https://app.mailerlite.com/users/login/) and follow the instructions below.
Click on your account name in the top right corner and select Integrations.
From the list of integrations that appears, choose Developer API, and click on the Use button.
This will display the API key.
Copy your API key and paste it into Integromat. Now you can continue and finish your scenario.