Incoming emails do not synchronise

Incoming emails do not synchronise

I receive notifications for opened email but I can't see the incoming responses and emails. how to solve it? 
One more issue while I do email settings is I receive this message : " You are yet to enable IMAP for your account. Access the link  https://www.zoho.com/mail/help/imap-access.html  to learn more. (Failure)" 
be noted that I can't access zoho mail as well.