How to extract data from custom WhatsApp Flows from?

Simplified scenario:

First, it is necessary to show a WhatsApp Flow form in WhatsApp. After the user fills it out, obtain the data from this form and save it in a database. Then, process the data and send it to the site via API.

I use the WhatsApp Business Cloud module to receive messages, but I cannot figure out how to get the values of custom WhatsApp Flow form fields.

Does anyone have any ideas on how to solve this?
Thanks.