1. Using Salesforce AppExchange to Install MailChimp for Salesforce (by MailChimp) 

This is a walk through of the Salesforce Lightning steps for using the Salesforce AppExchange Marketplace to select and install the MailChimp for Salesforce App (v1.80) that is supported by MailChimp. Note that MailChimp does not encourage you to implement this App in a Sandbox. The next video will show how to authenticate and configure the MailChimp for Salesforce app within Salesforce.
Here are the videos in this playlist:
1. Using Salesforce AppExchange to Install MailChimp for Salesforce (by MailChimp)
2. MailChimp for Salesforce (by MailChimp) Authenticating using Lightning
3. MailChimp for Salesforce App: Field Mapping for Integration
4. MailChimp for Salesforce App: Access using Lightning Permission Sets
5. MailChimp for Salesforce App: Modifying Page Layouts in Lightning
6. MailChimp for Salesforce App: Sync Settings in Lightning