What stops me from installing all those libraries is that the IT that made the HPC installation said it was not necessary because the architectures of the nodes were very similar. But then I tried to install a few programs and I did not find the way, unless the libraries were also installed in /usr/lib at each CN. I asked the IT for clarification but his company required 3000€ for that. After a few weeks struggling and looking for info, I had the suspicious that maybe the IT was wrong, but since I am a newbie I wanted to be sure.

I have followed your answers and everything works fine in the CN. Many thanks!!