How to make it work on Laradock

[pathros]

I have installed this Spatie's Laravel Backup package locally in Laravel Homestead.

If I run
php artisan backup:run
everything works fine.

However, in Laradock, when running that same command artisan backup:run right inside the workspace container, where the Laravel app is located, I get the following error:

Backup failed because: The dump process failed with exitcode 127 : Command not found : sh: 1: mysqldump: not found

My .env in Laradock is:

DB_CONNECTION=mysql
DB_HOST=mysql
DB_PORT=3306
DB_DUMP_PATH='/usr/bin/'

And the database.php file

'mysql' => [
   'driver' => 'mysql',
      'url' => env('DATABASE_URL'),
      'host' => env('DB_HOST', '127.0.0.1'),
      'port' => env('DB_PORT', '3306'),
      'database' => env('DB_DATABASE', 'forge'),
      'username' => env('DB_USERNAME', 'forge'),
      'password' => env('DB_PASSWORD', ''),
      'unix_socket' => env('DB_SOCKET', ''),
      'charset' => 'utf8mb4',
      'collation' => 'utf8mb4_unicode_ci',
      'prefix' => '',
      'prefix_indexes' => true,
      'strict' => true,
      'engine' => null,
      'options' => extension_loaded('pdo_mysql') ? array_filter([
         PDO::MYSQL_ATTR_SSL_CA => env('MYSQL_ATTR_SSL_CA'),
       ]) : [],
      'dump'=>[
         'dump_binary_path' => env('DB_DUMP_PATH'), // only the path, so without `mysqldump` or `pg_dump`
         'use_single_transaction',
         'timeout' => 60 * 5, // 5 minute timeout
         //'exclude_tables' => ['table1', 'table2'],
         //'add_extra_option' => '--optionname=optionvalue',
         'add_extra_option'  => '--host='.env('DB_HOST'), 
       ]
],

I want to point out that in Laradock the database already works fine (users can register, login, etc.). But then why doesn't it work with the php artisan backup:run?

Does anybody know how to make it work in Laradock?

What am I missing?