Documentation
Installation
Installation Methods
Composer
Flow PHP Releases Explained
If you want to work with JSON/CSV files here are the dependencies you will need to install:
composer require flow-php/etl:~0.13.1 flow-php/etl-adapter-csv:~0.13.1 flow-php/etl-adapter-json:~0.13.1
Flow is developed as a monorepo to reduce maintenance overhead and to make it easier to manage dependencies between components.
Instead of installing whole repository with all dependencies, it's recommended to install only the components you need.