Header file seems to not be loaded

Windows 10
platformio ide 2.2.2
cli 3.6.1a4
linter 2.2.0
autocomplete-clang 0.11.5
Python 2.7.13
using atom

Hey everyone, I’m very new to embedded systems in general (Really sorry if I posted this in the wrong category) and I am experiencing building errors with platformio. I cloned a repository created by a friend, who has no problem compiling. When I try to do so, I get a lot of errors with “<…> not declared in this scope”. I would normally look if I made a coding error, but because my friend does not get any such error I think there is something else going on.
All variables come from a config.h header file, and they are declared using #define … . If I include the header file in my main.cpp file, no change made. If I define it again in the main.cpp file, I get a warning saying “<…> redefined”.

I tried to tick" use developer mode" in the settings, but nothing happened. If I click “rebuild C/C++ project index” nothing seems to happen.

Could you provide a link to this repository?