You've successfully installed the Shopify app, however you notice that there is an error appearing within it when you view the app on tickets.
When you view the Shopify app on tickets after installation, you can see an error appearing as per the example screenshot below.
This is expected behaviour and your app is not broken!
When you see this error, it means the app is working, however the data between the ticket and the app are not matching.
In order for the Shopify app to populate customer order data, the app requires the email address which is used on the order, to be exactly the same as the email address which the customer is contacting you on the ticket via. If the email address' do not match, then the app will display this error.
Please check from here that the email address of the ticket requester is the same as the email address linked to the order in Shopify; Providing they are matching, data will then populate in the app as expected.