This issue arises when you have another hosted desktop session still logged on with your Outlook open.
When you try to open your Outlook for a second time the below error occurs:
Log off your current hosted desktop session and restart your device to ensure all hosted desktop sessions are logged off. Also, remember to check any other devices that may still have an active hosted desktop session of yours open eg. iPad.
If this still does not allow you to open your outlook when you log back onto hosted desktop, please contact Lets Operate Support on 0818 333 639 or firstname.lastname@example.org