We recommend you save both the welcome and abandoned cart emails as a template to speed up the recreation process. To learn more, check out reuse an email campaign layout as noted in Mailchimp's knowledge base.
Connect to Mailchimp - click the green Connect button
Authenticate to Mailchimp - when the pop-up window appears, add your Mailchimp username and password.
Select an Audience - choose a list to sync customers and their purchase data to Mailchimp. Please note: you may only send store data to one Audience.
Toggle double opt-in (Optional) - if you would like to change the double opt-in preference on the list that is connected, you may change it here.
Map merge tags (Optional) - choose which information you sync to Mailchimp by mapping Shopify data to Mailchimp merge tags (Email addresses are automatically synced from Shopify to Mailchimp).
Start sync - once initiated, ShopSync will sync all the information in your store to Mailchimp, including customers, orders, and products. Syncing also includes any merge tag mappings that have been set up.