1.  Confirm that the username and password being used are exactly the same.  One user might have two different hosting credentials that have different sets of permissions attached.

2.  Verify that the URL being used is the same. If the person has two different ways of accessing the hosting environment, it is possible that one URL that is linked on a website may be pointing to the incorrect location.

A good way to test is to have the user type the exact URL into the browser address bar and sign in.  If the available apps are correct, then bookmark the address for future use.  Also check the link on the organization website to ensure it is pointing to the correct location.