Php versions – Issue with laravel 5.8 and mongodb 4.2 connection

My system has 2 xampp’s one with PHP 5.6 and the other with PHP 7.3. I have correctly included both the PHP versions in environment variables. I am trying to connect my laravel v5.8 application with mongodb v4.2.

I have used jenssegers/mongodb package in my application. Also I have added MongodbServiceProvider in app.php. I am using Robo 3T for mongodb GUI. Now whenever I try to post data to mongodb collection then I get a authentication failed error.N= Below are the codes that I have used in my application.

Database.php(Config folder)

'mongodb' => [
            'driver'   =>  'mongodb',
            'host'     =>  env('MONGO_DB_HOST', 'localhost'),
            'port'     =>  env('MONGO_DB_PORT', 27017),
            'database' =>  env('MONGO_DB_DATABASE'),
            'username' =>  env('MONGO_DB_USERNAME'),
            'password' =>  env('MONGO_DB_PASSWORD'),
            'options' => []
        ],

Todo.php(Model)

namespace App;

use JenssegersMongodbEloquentModel as Eloquent;

class Todo extends Eloquent
{
    protected $connection = 'mongodb';

    protected $collection = 'todo';

    protected $fillable = [
        'title', 'desc'
    ];
}

.env file

MONGO_DB_HOST=127.0.0.1
MONGO_DB_PORT=27017
MONGO_DB_DATABASE=mongocrud
MONGO_DB_USERNAME=
MONGO_DB_PASSWORD=

Overview of Error message:

(1/1) AuthenticationException
Authentication failed.

in Find.php line 299
at Server->executeQuery('mongocrud.todo', object(Query), array('readPreference' => object(ReadPreference)))
in Find.php line 299
at Find->execute(object(Server))
in Collection.php line 624
at Collection->find(array(), array('typeMap' => array('root' => 'array', 'document' => 'array'), 'readPreference' => object(ReadPreference), 'readConcern' => object(ReadConcern)))