@AzorAhai-him- a "discussant" is a scientist. The presenters of the papers send their full paper to the discussant before the conference. The discussant reads the paper with a critical mindset. At the conference, after the presenters have presented their paper, it is the turn of the discussant to talk. He/She will highlight the strongest and weakest points of each paper, giving the presenters suggestions on how to improve their paper, and talk points for the audience

In Ubuntu you need additional packages for the R scholar package to be correctly installed: sudo apt-get install --assume-yes libudunits2-dev libcurl4-openssl-dev