To integrate with MailerLite, simply follow the steps below:

1. Log into your LeadsTunnel account.
2. On the left navigation menu, click on your account email to expand the drop down menu. Then, select "Account".

3. Click on "Integrations".

4. Under "Integrations", click on the "Add New Autoresponder/ CRM" button.
5. Select "MailerLite" from the Autoresponder System drop-down menu.

6. Log into your MailerLite account.
7. On the top right corner, where it shows your account name, click to expand a drop down menu. Then, select "Integrations".

8. Under "MailerLite API", click on the "Use" button beside "Developer API".

9. Copy the API key under "API Key" back to LeadsTunnel.

10. Finally, name your CRM (Note: The CRM name is for internal use only, so you can name it to anything).
11. Click "Save" to complete the integration.

Note: MailerLite does have a double opt-in feature, you will need to disable it by following the steps in this article. Otherwise, your leads will be required to confirm before they can be added to the email list. To disable double opt-in from MailerLite, please visit their knowledge base.