I’ve not compiled OwlSim in a long time…!
I think the problem stems from both OWL and Juce code having a class called AudioBuffer.
There is a setting for Juce called DONT_SET_USING_JUCE_NAMESPACE which disables the using namespace juce directive. Perhaps try that?
Or try changing the header include order. I’ll see if I get a little bit of time to run this build on a Win machine soon.