Cannot login

Cannot login

I have a user who cannot login. He appears to be in a loop while logging in. From his PC he open Zoho Books is prompted for his user name. He enters his username then get a message to "Verify Push Notification".  However he never receives a notification on his phone. When he opens the OneAuth app on his phone he again is notified to verify the push notification but the numbers in the notification are different. They appear to be out of sync.