I got this to work on my machine in kubuntu 20.04 LTS and Ubuntu 20.04 LTS (although I did more extensive testing in kubuntu.)
As Hunter indicated, you need to change all of the imports from PyQt4 to PyQt5, but PyQt5 uses slightly different syntax. Wherever you see a PyQt4 import statement in the python files change it to:
from PyQt5 import QtGui, QtCore
from PyQt5.QtCore import *
from PyQt5.QtGui import *
The files that need changing are:
Also, you need to find/replace all the instances of .setMargin(0) to .setContentsMargins(0,0,0,0) in the _GUI/hydra_main_window_layout.py file. I think there are 4 occurrences.
Finally, You need to install python3-pyqt5 and libffi7 (sudo apt install python3-pyqt5 libffi7)
I forked the ksdr github repo and created a new branch called PyQt5 and I also created a draft pull request for it. If anyone wants to test it and let me know if it works ok for you too, that would be great. Otherwise, you can just make these modifications manually.
If it doesnt work for some reason, please turn up logging in the run.sh file and check what the error messages are. The logging can be helpful. (see the end of the readme for how to turn up logging.)