If you are using Outlook 2010 or if you need to use Meeting+/Welcome+ on behalf of others, you need to use our VSTO add-ins for Outlook, which are add-ins that are locally installed.
To learn more about VSTO add-ins, click here.
However, when the VSTO add-in has been installed it will only appear in the Outlook ribbon when it can be used. This means that if you create an appointment in Outlook, it is only the Workplace add-in that will be visible, as the Meeting+ and Welcome+ add-ins cannot be used with appointments since appointments do not have a meeting room as a location.
If you invite either other people or add a meeting room the appointment automatically turns into a meeting, but the Meeting+ and Welcome+ add-ins will not appear until the meeting invitation has been sent and you reopen the meeting.
Why does it work this way?
It is a function in Outlook that all VSTO add-ins that cannot be used with appointments or unsent meeting invites are hidden from view in the Add-ins tab of the ribbon. In the case of the Meeting+ and Welcome+ VSTO add-ins, it is because they are meant to be used after a meeting room has accepted the meeting invitation.