The Node instructions for macOS don't work with System Integrity Protection. The instruction try to create a symlink at /usr/bin, which is no longer available to us. The new location is /usr/loca/bin
Instead of:
sudo ln -s ~/.joplin-bin/bin/joplin /usr/bin/joplin
The documentation should say:
sudo ln -s ~/.joplin-bin/bin/joplin /usr/local/bin/joplin