Can't export height maps using Basic demo version

Hi, I’m evaluating WB and just downloaded the basic demo version. I set up a simple network and I have two issues. First, when I build the world the build window just flashes on the screen briefly and goes away and it doesn’t appear that anything happens. Second, if I try to write the output to disk from any of the heigh output nodes, I get an error message and the file is not written. What is this new guy doing wrong? I’m on Windows 10.

I have attached the node graph, the settings for my height map output and the error message. Thanks.