Although the book does not mention it, nodejs and npm need to be installed first.
See this website:  https://www.golinuxcloud.com/install-nodejs-and-npm-on-raspberry-pi/

see the note at the end of step 1 before installing nodejs.
 

Hi.
What operating system do you have installed on your Raspberry Pi?
Usually, the command we use will automatically install those.
Our instructions are based on the official installation page. See here: https://nodered.org/docs/getting-started/raspberrypi
 
Regards,
Sara

Thank you for responding.  I am running raspberry pi os 64 bit on a Pi 4B.  I ran update/upgrade before I started the installation.  I am not a Linux expert, so I couldn’t follow the entire install script, but I noticed that it looked for NPM and bombed after it couldn’t find that.  After installing NodeJS and NPM, I successfully re-ran the installation and am now merrily learning about nodes.  The rest of your installation instructions were very helpful, as have been the other guides I have bought from you.  

Hi.
Thanks for your feedback.
I’ll test the instructions again on a new RPi installation.
 
I’ll mark this issue as resolved. If you need further help, you just need to open a new question in our forum.
Regards,
Sara