Setup Drupal 9 with acquia BLT

First we will create a Drupal 9 project with the recommended template using the below command.

composer create-project drupal/recommended-project blt-drupal --no-install

This will create a project with the name blt-drupal, since Acquia BLT requires a document root to be docroot, so let's update the project's composer.json file accordingly.

Now cd into the project folder and add acquia/blt into the project.

cd blt-drupal
composer require acquia/blt

Update your database credentials in local.settings.php and blt setup.

blt setup

We are all set to use the site.