To build ensure the 'public.sdk', 'plugininterfaces' and 'vstgui' folders from the Steinburg VST SDK are in the 'shared' folder
On Mac set an alias in ~/.zshrc for 'projucer' pointing to the projucer executable.
E.g: alias projucer=~/Documents/Personal/JUCE/Projucer.app/Contents/MacOS/Projucer