I recently ran into a couple of issues with the AWS CLI and ZSH on my Macbook.

I installed the AWS CLI with Pip and it seemed to be working as expected after the configuration.

The first issue I ran into was trying to setup the command completion with ZSH. After adding source /usr/local/bin/aws_zsh_completer.sh to my .zshrc file I got an error: complete:13: command not found: compdef.

I found a few results with no context, or relating to oh-my-zsh, and ZSH on an EC2 instance, but nothing that really helped.

Eventually I re-ran the ZSH New User Install Script,

autoload -U zsh-newuser-install
zsh-newuser-install -f

and making sure to include the options for auto completion which got things working. I think that for whatever reason in my old .zshrc file compinit wasn't loading properly.

After that I ran into another error:

zsh compinit: insecure directories, run compaudit for list.
Ignore insecure directories and continue [y] or abort compinit [n]?

This was a little easier to resolve and came down to permissions on the files as documented in this Stack Overflow answer.

cd /usr/local/share/
sudo chmod -R 755 zsh
sudo chown -R root:staff zsh

Finally everything was working as expected.

Working autocomplete