Invited user cannot join

Invited user cannot join

In Zoho books, I invited another admin user.  The link went to their email.  When the link is clicked on, it goes to the sign in page.  However, the user doesn't have a password to login with.  

Trying to use the sign up for an account link brings up the response, "that email address already has an account."

Using Forgot Password, it brings a response "user is inactive."  However, the user is not marked as inactive.