Failed to install Relaxed on Ubuntu18.04 on EC2

Procedure:

Step1.

Launch a clean Ubuntu18.04, login with default user ubuntu

Step2.

#node -v v8.10.0

#sudo apt-get update -y #sudo apt install npm #sudo npm cache clean -f #sudo n stable

#node -v v12.18.3

Step3.

#npm i -g relaxedjs

I know the README tells me not to use sudo but I met permission error so I gotta have a try #sudo npm i -g relaxedjs

Not sure if there's any prerequisites I miss? Thanks!