On Mac OSX, do the following in a terminal. A similar form should work on Windows/Linux (see whether you need to use pip3 and python3 for Python3). /Applications/[MATLAB]/ should be where your particular Matlab distribution is installed. On my machine it is /Applications/MATLAB_R2019a.app/ .
sudo pip3 install --upgrade pip
sudo pip3 install jupyter
sudo pip3 install matlab_kernel
cd /Applications/[MATLAB]/extern/engines/python
sudo python3 setup.py install