Normally that message would indicate that perhaps you have version 10 of the product and are trying to open version 11.
Or, perhaps you have multiple folks using version 11 and one person updated version 11 with a service release and worked on the project. In that case, others would need to update with the same service release.
Your IT was probably unable to download RH8 as it is not available. As Rick suggests, I bet they downloaded the latest version RH11.
Updates can be obtained from Adobe - Support : RoboHelp Support Center : Service Releases
Provided the project you are trying to open has not been opened in Rh11, then after applying the patches it should open in 8. It is important the Rh8 patches are applied before opening any projects as one of them fixed a particularly nasty bug.
See www.grainge.org for RoboHelp and Authoring tips