One calm install
The install block must come from nodejs.org. Paste the whole block into iTerm2. Press Return if asked.
Run what Node.js gives you
Type only the lines marked TYPE THIS. Do not type lines marked MAC REPLIES or NOTE.
TYPE THIS
open https://nodejs.org/en/download/NOTE
Copy the full current LTS command block from the official page.NOTE
Paste that official block into iTerm2. Let each command finish.What success looks like
iTerm2 may print a lot of lines. That is normal. When the prompt comes back, move to the next lesson.
If something feels wrong
Do not paste forum commands. Stop and ask. Use one official install path.