Just install and configure to map the zendesk fields to the mailchimp fields and you will have a fuly functional solution to allow you to push contact data from Zendesk to Mailchimp.
V2.0.1 Released June 2020 - now fully working and fully compliant with both the latest Zendesk App Framework v2 and latest Mailchimp API definitions.
Full Walkthrough - Is Zenchimp for me?\ \
Fullscreen Screenshots\ \ \ \ Sync Popup Window (out of sync) Sync Popup Window (in sync)\ \ \ Examples showing the different plugin states\ \ \ \ App Settings Screen\ \ \ There's a spreadsheet included which helps you to generate the Zendesk<-->Mailchimp field mapping settings\ \ \ Please submit bug reports Here: https://github.com/up-n-running/ZenChimp-Zendesk-App-Mailchimp-Sync/issues \ \ Pull requests are welcome. Team work makes the dream work.