unable to download WPLMS User Generated Quiz

I have purchased all addon pack. unable to download WPLMS User Generated Quiz on clicking download, following error appears Fatal error: Uncaught InvalidArgumentException: Found 2 errors while validating the input provided for the GetObject operation: [Key] is missing and is a required parameter [Key] expected string length to be >= 1, but found string length of 0 in /home/wplmssetup/public_html/wp-content/plugins/edd-amazon-s3/vendor/aws/aws-sdk-php/src/Api/Validator.php:65 Stack trace: #0 /home/wplmssetup/public_html/wp-content/plugins/edd-amazon-s3/vendor/aws/aws-sdk-php/src/Middleware.php(79): Aws\Api\Validator->validate('GetObject', Object(Aws\Api\StructureShape), Array) #1 /home/wplmssetup/public_html/wp-content/plugins/edd-amazon-s3/vendor/aws/aws-sdk-php/src/S3/S3Client.php(421): Aws\Middleware::Aws\{closure}(Object(Aws\Command), NULL) #2 /home/wplmssetup/public_html/wp-content/plugins/edd-amazon-s3/vendor/aws/aws-sdk-php/src/S3/S3Client.php(444): Aws\S3\S3Client::Aws\S3\{closure}(Object(Aws\Command), NULL) #3 /home/wplmssetup/public_html/wp-content/plugins/edd-amazon-s3/vendor/aws/aws-sdk-php/src/S3/S3Client.php(378): Aws\S3\S3Client: in /home/wplmssetup/public_html/wp-content/plugins/edd-amazon-s3/vendor/aws/aws-sdk-php/src/Api/Validator.php on line 65