I’ve set the visibility to public. But it doesn’t work. Can anyone help me?

'spaces' => [
            'driver' => 's3',
            'key' => 'your-key',
            'secret' => 'your-secret',
            'region' => 'your-region',
            'bucket' => 'your-bucket',
            'visibility' => 'public',
],

Tested and it’s working:

1) install v.1 of league flysystem library (documentation)

user@machine:~$ composer require league/flysystem-aws-s3-v3:^1.0

// 2) php code

class DigitalOceanSpacesClient {
   protected $privateKey;
   protected $publicKey;
   protected $path;
   protected $bucket;
   protected $region;
   protected $version;
   protected $spacesEndpoint = 'https://BUCKET.REGION.digitaloceanspaces.com';
   protected $error = false;
   /** @var boolean $log If you should log errors and properties for debuging */
   protected $log = false;

   /** @var \League\Flysystem\Filesystem $client The `\League\Flysystem\Filesystem` class object */
   protected $client;

   /**
    * Constructor.
    * 
    * The passed argument is a hash array with the following keys and types:
    * ```
    * string privateKey
    * string publicKey
    * string path
    * string bucket
    * string region
    * string version
    * bool log
    * ```
    * 
    * @param array[] $arr A hash array of key-values for the class properties
    * 
    * @return DigitalOceanSpacesClient A DigitalOceanSpacesClient object
    */
   public function __construct(array $arr = array()) {
      $this->privateKey = @$arr['privateKey'];
      $this->publicKey = @$arr['publicKey'];
      $this->path = @$arr['path'];
      $this->bucket = @$arr['bucket'];
      $this->region = @$arr['region'];
      $this->version = @$arr['version'];
      $this->log = (bool)@$arr['log'];
      $this->setSpacesEndpoint($this->bucket, $this->region);
   }

   /**
    * Dependency inversion principle.
    * 
    * @return \League\Flysystem\Filesystem A `\League\Flysystem\Filesystem` object
    */
   public function getClient() {
      if(!isset($this->client)) {
         $options = [

            /*
             * version 2
            'driver' => 's3',
            'key' => $this->publicKey,
            'secret' => $this->privateKey,
            'region' => $this->region,
            'bucket' => $this->bucket,
            'endpoint' => $this->spacesEndpoint
            */

            'credentials' => [
               'key'    => $this->publicKey,
               'secret' => $this->privateKey,
            ],
            'region' => $this->region,
            'version' => $this->version,
            'endpoint' => $this->spacesEndpoint

         ];
         // This is my custom method at Flysystem as I don't
         // use composer and I want global functions to load
         // on demand - don't care about composer's approach; 
         // just skip it if you use composer :((
         //\League\Flysystem\Utils::run();
         $client = new S3Client($options);
         $adapter = new AwsS3Adapter($client, $this->bucket);
         $this->client = new Filesystem($adapter);
      }
      return $this->client;
   }

   /**
    * Calculates spaces url based on object properties.
    * 
    * @param string $bucket The Spaces name
    * @param string $region The Spaces region
    * 
    * @return void
    */
   public function setSpacesEndpoint(string $bucket, string $region) {
      if($bucket && $region) {
         $this->spacesEndpoint = \str_replace(['BUCKET.', '.REGION.'], [$bucket . '.', '.' . $region . '.'], $this->spacesEndpoint);
      }
   }
}

3) Now, it’s easy to build a \League\Flysystem\Filesystem object

   $arr = array(
         'log' => false,
         'privateKey' => 'private key',
         'publicKey' => 'public key',
         'path' => 'a filepath',
         'bucket' => 'spaces name',
         'region' => 'e.g. ams3'
      );
   $test = new DigitalOceanSpacesClient($arr);