Extracting the files

The first step of adding an extension is getting its folder into extension/. Pick the way that fits; all three end with the same folder.

With Composer (recommended)

An extension published as a Composer package with the install type ezpublish-legacy-extension lands in extension/ by itself:

composer require se7enxweb/ezflow

With composer config --global 'preferred-install.se7enxweb/*' source set once, Composer makes it a Git clone with its history instead of a release archive.

By copying the folder

From a release archive, or a Git clone of an extension that composer.json does not require:

cd extension
git clone https://github.com/se7enxweb/ezflow.git ezflow
cd ..

Do not clone by hand an extension Composer installed: its next update replaces the folder, history and commits included. Let Composer make the clone (composer reinstall after the setting above).

From a package

php ezpm.php import /path/to/ezflow.ezpkg

The package installer can write content: try it on a copy of the site first. php ezpm.php help lists the package commands.

Check

ls extension/ezflow/ezinfo.php extension/ezflow/extension.xml

Both file names should be printed. The folder name must be the extension's name. Next: Activating the extension.