"My Domain" is the primary domain on your store. Below are details on how this works on both Shopify & WooCommerce stores.
In order to function correctly, Cardzware requires your store to have a domain.
As long as you have set up a primary domain in your WooCommerce admin, you will be able to set up your subdomain.
If you haven't added a domain to your store yet, it will default to the *.myshopify.com domain. You cannot add a subdomain until you add a domain to your store via Shopify Admin.
You can still test/play with the Cardzware App, but it will only work in the Chrome browser (do not use Incognito/Private Browsing mode).
In order to function correctly, Cardzware requires your store to have a domain. You can add a new domain to your store here:
For more information you can read Shopify's FAQ on adding domains here:
Once you have successfully connected a domain to your store it will automatically update here and you will be able to setup the subdomain.