I am using this API which works fine:  https://www.zoho.com/campaigns/help/api/add-contacts-existing-list.html it is good because the subscriber does not have to confirm their email address. 

But I need the features this API has

specifically the ability to add customer fields like first name, last name, and company:  https://www.zoho.com/campaigns/help/api/contact-subscribe.html

but WITHOUT the subscriber needing to confirm. 

Please help me out thanks.