After your account is connected,
visit the accounts page for the channel you want to manage messages for,
then, click the Email Forwarding button in the Actions column:
Quick links to account pages:
You will then be shown a couple of steps to set up email forwarding. After completing them, you can then use Customer Service to manage messages from this selling channel.
If you don’t yet have a Shopify store, you can create one for free here:
👉 https://shopify.pxf.io/Y9yRWK