Unfortunately, it is not possible to use custom liquid templates in OrderlyPrint for performance reasons. The documents in OrderlyPrint are more limited due to the higher number of documents that can be created at once. It's okay for apps that process 50 orders at a time, but OrderlyPrint allows up to 500 orders.
The app was designed to bulk print and fulfill. Thus, it needs to be fast, which isn't possible with custom liquid templates.
The customizations of OrderlyPrint are limited to what's in the editor, but the app offers three built-in designs for your documents that you can use. For that:
Login to OrderlyPrint (Shopify admin -> Apps)
Go the Settings -> Document design page
Go into the Theme, styling and layout section of the editor
Scroll down to the DOCUMENT THEME section of settings
Select your preferred theme style.
Note: The templates form the Order Printer Templates app can only be exported to either the Shopify Order Printer app or our Order Printer Pro app.
Any additional questions about OrderlyPrint? Reach out to us at any time!