Make sure when customers checkout, they are added to your loyalty program.
You can access these settings in your BigCommerce Store Settings. Go to Store Setup> Store Settings>Display
BigCommerce Customer Account settings
Customers are automatically added to your loyalty program when they create a store account. They can do this by making a purchase online or by creating an account through your loyalty widget.
To make sure that customers can create a store account, check your BigCommerce Account Creation settings.
Under Store Setup> Store Settings>Display, set your BigCommerce Account Creation setting to: Yes, enable account creation in my store
Your customers will have the option to create a store account or check-out as a guest. In both cases your customers will be added to your loyalty program and earn points for their purchase.