How to resolve the Composer related error shown using the Drush DL command? I am working on MAMP and I have already installed a Drupal 7 site in my local machine ( not using Drush or Composer ). Then I have installed Composer and Drush ( Installing Drush on MAMP ). Now my Drupal site is under htdocs folder and it's working. If I run "drush" from htdocs via the command line, then it's shown a bunch of help command list. 

But if I am trying to install any module using drush dl Module_Name then it gives me an error like so:


  [error]  dl has been deprecated. Please build your site using Composer. Add new projects with composer require drupal/[project-name]. Use https://www.drupal.org/project/composer_generate to build a composer.json which represents the the enabled modules on your site.


Can anyone tell me what the problem is? Do I need to install a fresh Drupal 7 site via Composer?
using composer is rather for Drupal 8 than Drupal 7
You could remove your version:

composer global remove drush/drush


and install an older one

composer global require drush/drush:8.*