Thanks for your answers.
Ok, actually I spent some times to make blu-rays work and I don't want to spend money and time if I'm not sure it will work.
By the way, the most updated libaacs.dll and libbdplus.dll I found I downloaded from here:
https://vlc-bluray.whoknowsmy.name/files/win64/
I have just a couple of blu-rays that won't play because of the libbdplus.dll.
I don't know where to find a more updated version.
By the way, searching for the player (I would buy only an external USB player), I've found a lot of player of unknown brand (Archgon, Techpulse...) and so I guess I won't be able to extract the keys and play 4K blu-rays with them.