How do I install Drupal Console to my project with Composer?
You should follow the docs on the official Drupal Console repo on how to install it with Composer. Note that the global launcher is not recommended, it is recommended to add it to your project through Composer.

https://github.com/hechoendrupal/drupal-console/blob/master/README.md

# Change directory to Drupal site
cd /path/to/drupal8.dev

# Download DrupalConsole
composer require drupal/console:~1.0 \
  --prefer-dist \
  --optimize-autoloader \
  --sort-packages


Note that the second command is all one command, not four. The \ tells terminal the command is continuing to the next line.