Visual Studio 2019 Compiling a DLL from Github Sourcecode - Oboe - c++

Question

I'm busy creating a music composer app for Android and want to use a Github repository called Oboe (1.3.1) in Unity 3D.
Here the link: Guithub repository for Oboe
This solution would provide me with native Android Audio funtions that I could use to pass by the native Unity 3D audio engine and could short a lot of latency, that it produces.
Unfortunatly this repository was rather created for use in Android Studio, to write code with it in Java or Kotlin, but it was written in C++. To use it in Unity 3D, I'd have to compile it into an DLL File, that Unity can accept by standard as a PlugIn.
To avoid having to write a Java wrapper in Android Studio, I chose for Visual Studio 2019 and installed all prerequisites for mobile development(xamarin), the Android SDKs from 4.1 Jelly Bean to 10.0 Q, Android SDK (&Platform-) tools and the NDK.
So I gues I'm pretty much set up for compiling with Android functions.
And here starts my confusion. I created a Universal Windows Project (as I want to compile into a DLL) copied the source code into reasonable folders concerning the paths in the scripts.
When I try to debug the project the compiler spits out hundreds of error messages, some of them concerning to native Android Audio functions that cannot be found. So I guess I just put the Error Messages here (I turned 'use precompiled headers' of in project settings, because all the header files are part of the repository):
1>------ Build started: Project: Oboe_1.3.1, Configuration: Debug Win32 ------
1>dllmain.cpp
1>AAudioLoader.cpp
1>D:\VisualStudioProjects\Oboe_1.3.1\Oboe_1.3.1\oboe\Utilities.h(20,10): fatal error C1083: Cannot open include file: 'unistd.h': No such file or directory (compiling source file src\aaudio\AAudioLoader.cpp)
1>AudioStreamAAudio.cpp
1>D:\VisualStudioProjects\Oboe_1.3.1\Oboe_1.3.1\src\aaudio\AAudioLoader.h(56,10): fatal error C1083: Cannot open include file: 'AAudio.h': No such file or directory (compiling source file src\aaudio\AudioStreamAAudio.cpp)
1>AudioSourceCaller.cpp
1>D:\VisualStudioProjects\Oboe_1.3.1\Oboe_1.3.1\oboe\Oboe.h(27,10): fatal error C1083: Cannot open include file: 'oboe_include/Definitions.h': No such file or directory (compiling source file src\common\AudioSourceCaller.cpp)
1>AudioStream.cpp
1>D:\VisualStudioProjects\Oboe_1.3.1\Oboe_1.3.1\src\common\AudioStream.cpp(18,10): fatal error C1083: Cannot open include file: 'pthread.h': No such file or directory
1>AudioStreamBuilder.cpp
1>DataConversionFlowGraph.cpp
1>D:\VisualStudioProjects\Oboe_1.3.1\Oboe_1.3.1\oboe\AudioStream.h(287,57): error C2061: syntax error: identifier 'clockid_t' (compiling source file src\common\AudioStreamBuilder.cpp)
1>D:\VisualStudioProjects\Oboe_1.3.1\Oboe_1.3.1\oboe\AudioStream.h(308,81): error C2061: syntax error: identifier 'clockid_t' (compiling source file src\common\AudioStreamBuilder.cpp)
1>D:\VisualStudioProjects\Oboe_1.3.1\Oboe_1.3.1\oboe\AudioStream.h(308,82): error C2556: 'oboe::ResultWithValue<oboe::FrameTimestamp> oboe::AudioStream::getTimestamp(void)': overloaded function differs only by return type from 'oboe::Result oboe::AudioStream::getTimestamp(void)' (compiling source file src\common\AudioStreamBuilder.cpp)
1>D:\VisualStudioProjects\Oboe_1.3.1\Oboe_1.3.1\oboe\AudioStream.h(287): message : see declaration of 'oboe::AudioStream::getTimestamp' (compiling source file src\common\AudioStreamBuilder.cpp)
1>D:\VisualStudioProjects\Oboe_1.3.1\Oboe_1.3.1\oboe\AudioStream.h(308,45): error C2371: 'oboe::AudioStream::getTimestamp': redefinition; different basic types (compiling source file src\common\AudioStreamBuilder.cpp)
1>D:\VisualStudioProjects\Oboe_1.3.1\Oboe_1.3.1\oboe\AudioStream.h(287): message : see declaration of 'oboe::AudioStream::getTimestamp' (compiling source file src\common\AudioStreamBuilder.cpp)
1>D:\VisualStudioProjects\Oboe_1.3.1\Oboe_1.3.1\src\aaudio\AAudioLoader.h(56,10): fatal error C1083: Cannot open include file: 'AAudio.h': No such file or directory (compiling source file src\common\AudioStreamBuilder.cpp)
1>FilterAudioStream.cpp
1>D:\VisualStudioProjects\Oboe_1.3.1\Oboe_1.3.1\src\flowgraph\MonoToMultiConverter.h(20,10): fatal error C1083: Cannot open include file: 'unistd.h': No such file or directory (compiling source file src\common\DataConversionFlowGraph.cpp)
1>FixedBlockAdapter.cpp
So that's just the smaller part of the error list. I googled a lot of these errors and found e.g.
that open include file: 'unistd.h : No such file or directory has to do with that this file is a linux file. But Android is a linuxoid OS so I cannot asses this error message.
Whereas: Cannot open include file: 'AAudio.h': No such file or directory points to a file that is not included in the Github repository at all, but should be part of the Android NDK, as it belongs to the native AAudio Android engine.
My question is, did I setup the project right? Is my approach reasonable? I'm unexperienced with both C++ coding and Visual studio. I even found a precompiled .arr library of this project, that I could use as PlugIn in Unity as well. But using a precompiled java library with funtions written in C++ and coding in C# does something strange to my brain convolutions. I tried even that though, so you might see how desperate I am for some good hints. Thank you and have a nice day!