The simplest and most reliable way of running the experiment was doing it from 'Psychopy Coder'. Simply, download newest version from https://www.psychopy.org/download.html and once you do run it, three windows should pop up 'PsychoPy Builder', 'PsychoPy Coder', and 'PsychoPy Runner'. In 'PsychoPy Coder' click a second icon from the left on the task bar which will open choose a file menu. Find 'libet.py' and hit enter.
Once you opened our script in 'PsychoPy Coder' click the play button and script should run while outputting its logs to 'PsychoPy Runner'.
Many thanks to @mcvinding, since the experiment script is based of his work.