I recently decided to utilize the C++ library called FreeGLUT to have a window be managed from my program, where I can draw things via OpenGL. But at the same time I saw some people telling that it is an old library, not that much reliable and so on... Should I keep using that or move to another one?
I would only recommend using FreeGLUT if you are just learning OpenGL and don't want to worry yourself with things like window and context creation.
FreeGLUT is also use full when you would want to create a quick graphics demo, something that purely shows off some graphics related concept.
Its otherwise a bad choice for games as you don't have control over the game loop and raw input collection, which are quite important for high performance games.
GLFW is a good alternative. It is still actively maintained, and easily allows creating an OpenGL context and window, supports multiple windows, and supports controller input.
There are tutorials on their website for using it, but if you are already used to FreeGLUT, this tutorial here may be of use, as this tutorial series primarily used freeglut but transitions over at this point in the series.