rclone ( http://rclone.org ) is the perfect tool for that. It is a command line program which tries to work like rsync except copying to cloud storage providers (Dropbox, Amazon Drive, S3, Google Drive, B2 etc) . By default it will copy the files 1:1 file to remote object.

I use it to share stuff on Dropbox. I run Linux and have never installed the Linux client (if there is one, I don't know!)

PS I wrote rclone!