apt update
apt upgrade
apt install -y zsh powerline fonts-powerline
chsh -s /usr/bin/zsh root

Now logout from the root user, log in again, and you will get the zsh shell.

    echo $SHELL

apt install -y wget git
wget https://github.com/robbyrussell/oh-my-zsh/raw/master/tools/install.sh -O - | zsh
cp ~/.oh-my-zsh/templates/zshrc.zsh-template ~/.zshrc
source ~/.zshrc

You may need to change theme to agnoster or similar for powerline fonts to work. If powerline fonts still not working try this: change font of terminal/editor to a powerline supported font. This is required for MacOS Catalina.

Install z zsh-autosuggestions

git clone https://github.com/zsh-users/zsh-autosuggestions ${ZSH_CUSTOM:-~/.oh-my-zsh/custom}/plugins/zsh-autosuggestions

Then add 'zsh-autosuggestions' to your plugins list in your zsh configuration file '.zshrc'

References:

• How to setup zsh and oh my zsh on linux
• What is ZSH, and Why Should You Use It Instead of Bash?
• Zsh tips and tricks, plus great OS agnostic installation method for oh-my-zsh
• The original git repo with installation instructions