The linked tutorial shows how to install Magento 1.9.x, but there have been a number of changes since the release of the 2.x series. One of those changes was to use Composer, a tool for handling dependencies for PHP projects, to install a number of PHP packages that are required for Magento.

After installing Composer, move to the root directory of your Magento installation and run:

composer install

This will download and install a number of packages to complete your installation.

You can also use Composer to completely install Magento, without the need to download the archive file manually:

composer create-project --repository-url=https://repo.magento.com/ magento/project-community-edition magento

This will require authentication with a Magento account .