Exportify supports Line Item Properties and Cart Attributes (aka Order Note Attributes).
There are two common ways custom fields are collected from customers when they purchase products from your Shopify store, and Exportify supports both of them:
Line Item Properties: These are custom fields set by the customer on each product in an order. Your Shopify theme would have been customized to collect these values. They appear on the order detail page on the Shopify Admin, not in the default Shopify order export file.
Cart Attributes (aka Order Note Attributes): Cart Attributes let you collect additional information about an order on the cart page. This information is relevant to the transaction and is not for product customization. For example, you may want to allow customers to choose one of several pickup locations for their order.
Exportify can be configured to extract Line Item Properties and Cart Attributes then output them in their own columns in your custom Exportify export file format.