Node.js must first be installed on your system. Installers for all systems are available from https://www.nodejs.org.
The Node.js package manager, npm, is necessary to install the zeromq sockets package for communication with the Node.js evaluator. Refer to Node.js documentation on how to install npm if it is not available with your installation.
Once Node.js and npm have been installed, the zeromq package can be installed using npm. By default, npm will install the package to a folder named node_modules, but for ExternalEvaluate to find the installation, it needs to be placed in a directory called .node_modules in the home directory.