Can't connect via ZohoCRM iPhone app

Can't connect via ZohoCRM iPhone app

Hello,

I can log into my Zoho CRM account using browser (both laptop and mobile) but the same ID / password doesn't work if I try to connect to my account using Zoho CRM app for iPhone 6 (latest iOS 8.2). When I enter my ID / password, I get an error message in an alert box with the message "USER_NOT_CONFIRMED". When I click "OK" button (the only button available), I am taken back to the main sign-in screen. Do I need to do something in the settings of my account to enable mobile access? I currently have subscription to "Standard Plan". Thanks.

-Satish