Are you an author using BookFunnel? Why not connect your account to MailerLite?
To integrate your MailerLite account with BookFunnel, go to your top right dropdown menu and choose Integrations. Choose BookFunnel and copy your account API key.
Now log in to your BookFunnel account. On the left-hand menu click Integrations and choose MailerLite. Then paste your MailerLite API key and click Enable MailerLite integration.
To see if the integration is working you need to add a new page.
Select a book and create a new giveaway page by clicking Yes, collect the readers email addresses. You'll be able to choose the group to sync with from your MailerLite account.