In both cases the main requirement to make the handshake was providing an API Key from MailerLite, which is available in your account. In case it helps, you can access the Developer API Reference Guides (Getting started | MailerLite developers website) for more details.
Folks, our former Wishlist portal, where our users shared their requests and suggestions, was transferred to this forum. You’re most welcome to vote, add new ideas, and leave your comments here — we surely will consider them all!