Account is disabled

Account is disabled

I have added a user to CRM from the super admin and send a invitation. However, the user cannot accept the invitation and when going to the CRM all we get is a little text in the browser saying : Account is disabled

When looking in the CRM under active users it clearly states that the user is active and an administrator....
as far as I know and can see this user is just part of that single organisation, but I find it hard in ZOHO to really confirm that.

At this point I am lost where to look.