Zoho Flow and Mailchimp

Zoho Flow and Mailchimp

Zoho Flow can fetch custom fields from Zoho CRM, but I want to send them over to Mailchimp for list segmention purposes. It appears that Mailchimp will only receive a static 5 or so fields from Zoho Flow (no option to add custom fields).  The desire is to build the list segments inside of Mailchimp based on field data from CRM.  Am I missing something key?  Or is there a better way to achieve this? SyncApps is too pricey and the Zoho Marketplace extension doesn't allow us to bring over custom fields either.  Thanks!