If you go here:
to the very end, I say how I installed it. I do this:
First, install it by:
sudo apt update
sudo apt install jupyter
pip install --upgrade ipykernel
pip install webgui_jupyter_widgets
jupyter nbextension install --user --py widgetsnbextension
jupyter nbextension enable --user --py widgetsnbextension
jupyter nbextension install --user --py webgui_jupyter_widgets
jupyter nbextension enable --user --py webgui_jupyter_widgets
I think the main thing is doing the sudo apt install jupyter, and the ipykernel.