The namespace shouldn't need removing as in the top of your INO you have "using namespace audio_tools;".

_Win32 is defined due to this being in windows, and if needed you can add #undef _WIN32 before the library header include.

Also the intellisense looked correct in your earlier image (below again) and if you add the "." to the end it would have shown the members of the Audio Tools object.

From what I can see there is no issue with Visual Micro here.

Thanks for the win32, diden't know how to solve that. 

I have replaced this

namespace audio_tools {

...

}

with using namespace and now it seems to work.