Compiling LiquidFun-Testbed Xcode 10.2 - Missing files on compile-time

Should these examples work out of the box?

I've been following the steps from https://github.com/cocos2d/cocos2d-x-samples exactly, namely

Download

$ git clone https://github.com/cocos2d/cocos2d-x-samples.git
$ cd cocos2d-x-samples
$ python download-engine.py

Running

Once the samples were downloaded just go any sample, and open the project. eg:

$ cd cocos2d-x-samples/samples/LiquidFun-Testbed/proj.ios_mac
$ open LiquidFun-Testbed.xcodeproj/

However, when I build the LiquidFun-Testbed.xcodeproj, I get

Showing All Errors Only

Prepare build
note: Using legacy build system


Build target libcocos2d iOS of project cocos2d_libs with configuration Debug


Build target LiquidFun-Testbed iOS of project LiquidFun-Testbed with configuration Debug

clang: error: no such file or directory: '/Users/Chris/Desktop/source/repos/3rd party libraries/cocos2d-x-samples/libs/liquidfun/liquidfun/liquidfun/Box2D/Box2D/Dynamics/Contacts/b2EdgeAndPolygonContact.cpp'
clang: error: no input files

clang: error: no such file or directory: '/Users/Chris/Desktop/source/repos/3rd party libraries/cocos2d-x-samples/libs/liquidfun/liquidfun/liquidfun/Box2D/Box2D/Collision/b2Distance.cpp'
clang: error: no input files

clang: error: no such file or directory: '/Users/Chris/Desktop/source/repos/3rd party libraries/cocos2d-x-samples/libs/liquidfun/liquidfun/liquidfun/Box2D/Box2D/Common/b2StackAllocator.cpp'
clang: error: no input files



Build failed    06.01.20, 22:25    698.2 seconds

Clearly, the compiler is looking for files in
/Users/Chris/Desktop/source/repos/3rd party libraries/cocos2d-x-samples/libs/liquidfun/liquidfun/liquidfun/Box2D/Box2D/

but these were never created.

After following the mentioned steps above, Box2D and its code are instead placed in
/Users/Chris/Desktop/source/repos/3rd party libraries/cocos2d-x-samples/libs/cocos2d-x/external/Box2D

...So why is it looking for these files in

/Users/Chris/Desktop/source/repos/3rd party libraries/cocos2d-x-samples/libs/liquidfun/liquidfun/liquidfun/Box2D/Box2D/??