A new way of distributing – simply download the AppImage and add this to your zshrc:

eval "$(…/z4-4.0.1,AppImage -ie)"

This command will load Zinit 4. The options are -i or --install and -e or --eval. You can also just install Zinit4, via:

…/z4-4.0.1,AppImage --install

and then load it normally via:

source ~/.local/share/zinit/zinit.bin/zinit.zsh

added to Zshrc. The --install command should be also placed there, it installs Zinit 4 just once