Zoho <--> Outlook sync plugin for calendar does not sign in

Zoho <--> Outlook sync plugin for calendar does not sign in

The Zoho plugin simply gives me:

"Zoho Business Plugin
You seem to have entered an invalid username or password. Please try again."

And I checked the sign-on with my calendar Profile, which is up and running fine.
I am using the email for the sign-on, the phone alternative is not activated.

Possible thoughts:
Last time I entered the calendar it was on a new browser and it confirmed by my cell phone SMS
It did warn me that my password was a little weak, but it said it is ok.

At this time I am only interested in calendar and would skip contacts if it loaded and asked.

Your thoughts?
Thanks!

Steven