In order to enable the purchase of goods or services on the website, you need to configure the categories. For each category, transactions are enabled and configured separately. You also need to select a payment system for secure transactions in the website settings under the integration section
Go to the category editing or after adding a category, go to the main tab and select the name of the products that will be in the category. Orders can only be placed for physical products, electronic products, and services.
Next, go to the properties tab and enable secure transaction
After enabling it, products in this category will have a Buy button.