Navigate to <https://apps.shopify.com/chaiport-payments>

Click "Add app" and make sure you are logged in to your Shopify store

In this screen, you can enable/disable the visibility of these icons on the Shopify checkout screen. This is just for the visual representation for the end- user and doesn't affect the functionality of payments processing. 

You "Enable test mode" for testing the payments flow before going live.

Finally, click "Activate PortOne Payments".

This completes the installation process of PortOne Payment App on a Shopify Store.