Initial Configuration
Once installed, visit within the Dashboard -> Shopify -> Configuration
Add your Shopify domain to this page, save, and continue following the displayed instructions to add in your API keys. Take particular note of the permissions options you need to set.
Beyond this, review the Cart and Product pages within the Shopify Dashboard section.
These options allow you to:
configure whether the checkout appears in a pop-up window or in the same window set a currency prefix and suffix (important to set if you are using a non-dollar currency in Shopify) override default text labels within the cart, and default text labels on the Shopify Product block enable or disable the buy button and cart controls (allowing you to effectively switch off ordering completely)