You'll need to go to this page of our website: https://www.zeidman.info/?dt_portfolio=chimpegration
Then, you'll click on the button labelled "Start Your Free Trial Now." (It's in the bottom right hand corner of the screenshot below.
You may also find this article on connecting the App helpful as you get connected. https://zeiddev.freshdesk.com/a/solutions/articles/236289
You can also read more about activation and authentication in Chimpegration for NXT in this section of the User Guide.