1. Login to your Mailchimp account‌

2. Get API Key‌

Click to account section in the header and click to menu "Account"

Then, click "Extras" -> "API Key" to go to the API page. Please copy the existing API or create the new API key you want.

3. Get Listing ID‌

Please click to menu "Audience" and click to "Settings" item in drop-down of "Manage Audience"

Then, click to menu "Settings" -> "Audience name and defaults" go get List ID

Example for MailChimp profile