You have two options to install Printess on your Shopify store:
You can simply install the Printess App via the Shopify app store. The Printess App automatically creates a new Printess account and all charges are done via Shopify.
Here you find the first steps tutorial, you need to do after the installation:
The second option works without a Shopify App and allows you to use your existing printess account. This path is definetely more “Nerdy” but it can be neccessary if you for example want to connect your existing Printess account with multiple Shopify Shops or other Plattforms.