Enabling Customer Registration in Shopify
If you are unable to register accounts as a customer, you need to enable Customer Registration within Shopify. Fortunately, this process is very simple.
Enabling Customer Registration
In the Customer Account Fields app, head to the Getting Started page and skip to Step 3. There will be a button there for Enabling Customer Registration. Click it and you will be brought to Shopify.
Tip: If this link doesn't work for you, go into Shopify > Settings > Checkout > Customer Accounts
Now that you are on the checkout settings page in Shopify, look for the Customer Accounts section. It may say disabled by default, change it to either Accounts are optional or Accounts are required.