How can I activate the Printify Shipping Calculator on my Starter plan?

[fredlite]

I signed up for the annual Starter plan so I can get access to the Printify Shipping Calculator, but the threads here keep mentioning the Shopify chat option, which cannot seem to find.

I came as far as to be able to enable it in the Printify back-office, but when I try to add a new rate for the Shopify shipping profile there is no app available. I just got this message: "There are no carriers or apps available for this zone."

Please advise how to proceed so I can start using the Printify Shipping Calculator.