How to activate Mailchimp integration

Provide API key to BI Book when activating. Here is instructions how to retrieve it:

ref: Marketing API Quick Start Guide | Mailchimp Developer

The simplest way to authenticate a request to the Marketing API is using an API key.

Here's how you can generate one for yourself:

• Navigate to the API Keys section of your Mailchimp account.

• Click Create New Key and give it a descriptive name that will remind you which application it's used for (BI BOOK). Copy the generated key immediately and store it in a secure location. You won't be able to see or copy the key once you finish generating it.