Step#1: Export Leads from Gumroad Log in to your Gumroad account. Navigate to the product dashboard and select the product used for collecting leads. Download the list of purchasers, which includes the email addresses of the people who accessed your freebie.
Step#2: Import Leads to Google Contacts Import the list of emails from Gumroad into your Google Contacts. [Using "Import" Tool]
Step#3: Add Google Contacts to Brevo @ https://app.brevo.com/integration-workflows/68d937ed107d8c195f2fbcaa/settings