The project uses GLFW3, GLM, OpenGL ES 3.0 and so consequently WebGL 2.0.
There is also a version here, which has support for textures.
In the public/src/main.cpp file I learned about the lambda capturing method for the emscripten_set_main_loop function from here.
To see this work simply do node install or yarn in the main directory, and then do node index.js and then go to localhost:2000 to see the sample running.
Emscripten SDK and required libraries are downloaded via compile.sh, which in turn invokes the script(s) in the include directory, which setup the header files and stuff as required, to compile the source code.
Learnt from here https://learnopengl.com/.