Zoho One and IMAP?

Zoho One and IMAP?

I'm having some confusion as to what Zoho One is equivalent to for the apps that have different levels.

I have Zoho One. When I try to enable IMAP in the mail app it tells me it's an extra cost option. 

However according to this document on the Zoho website it should be included. Which is it? Am I doing something wrong? I am trying to enable IMAP to use MS Outlook and to use IMAP with Zoho CRM.
https://www.zoho.com/one/plan-details.html


thanks.