Error uploading a file to ASW S3 with L5

Hello, I'm learning how to upload a file to S3 of AWS, and I was following along the video "Multiple Filesystems", so I have my class that is calling the Filesystem

use Illuminate\Contracts\Filesystem\Filesystem;

with the function

public function index(Filesystem $filesystem){
        $filesystem->put('hello.txt');
        return 'I work!';
}

and I'm specifying the driver in the filesystem to s3 with the key, the secret the region 'US Standard' and the bucket, also the bucket has the permitions to "Everyone" justo to view permisions, and "Authenticated Users" to upload/delete. Also I'm using the repositori aws/awssdkphp 2.7 installed with composer. But when I run the code I get this error

FatalErrorException in FilesystemManager.php line 140: Class 'League\Flysystem\AwsS3v2\AwsS3Adapter' not found

And I hvae no idea what to do. I hope you guys can give me a hand. Thanks.