Hi everyone,
I found the solution, and it was simple. My build of Ubuntu 20.04 LTS was lacking a library called libglut.so.3 which is part of the package freeglut3. I just didn`t see the error at the start of the program analysis before. I`m blind!
By a simple
$ sudo apt install freeglut3
Now it works perfectly. I had this exact same problem when i tried an installation of 18.04 LTS. It could be nice if it was somewhere in the installation documentation!
Have a nice day !