When I try to access the uploaded files from mine S3 account using your S3 addon it gives me an error
S3::getBucket(): [InvalidRequest] The authorization mechanism you have provided is not supported. Please use AWS4-HMAC-SHA256. - /var/www/html/wp-content/plugins/wplms-s3/includes/class.s3.php:445 Code: 0
Well please try creating your bucket in the region in which version of s3 api is supported :
https://docs.aws.amazon.com/general/latest/gr/rande.html#s3_region
version 4 s3 api support is being added and update for this might be releasing in upcoming week