In order to work properly, it needs git, phpcs and phpcbf to be installed
Location of their bin can be provided with environment parameters (see source code)
To avoid committing code with check style issues, download the file and you can add a git hook on pre-commit:
ln -s /path/to/phpcs-pre-commit .git/hooks/pre-commit
If errors are found it will try to fix them with phpcbf if you agree
The standard to check against is PSR2 by default but can be overriden with STANDARD environment parameter
P.S.: /path/to/phpcs-pre-commit should be executable
chmod +x /path/to/phpcs-pre-commit
you can install hooks globally
https://coderwall.com/p/jp7d5q/create-a-global-git-commit-hook