I contacted filter forge directly and I got the following reply
"Hi whowell,
The Compare Editions chart puts it right -- bump, normal and other maps can only be rendered with Filter Forge Professional.
The demo version is, in fact, the Professional edition, only with the time limit -- its task is to show the users all the Filter Forge features, which is why it can generate maps.
Let me know if I can be of any further assistance.
Best regards,
Bella Beygelman, Filter Forge Support,"
So it looks like I have to get the Professional edition if I want to use bump and normal maps