Is there a way LOAD CSV can access a file on s3 without making it public?
I'm not an expert of S3, but you can mount locally the S3 bucket.
Or if you have an HTTP or FTP server, you can add the login/password in the url of the CSV file.
You can also generate temporary accessible s3 buckets or restrict them to source-ip's or such.
We don't support aws credentials in LOAD CSV. It could be something that could be added to APOC though.