I've tried this and it works but there is a big issue, I'm not able to set "Path".
I can only send backups to bucket's root directory, path must be "/". Anything else (eg. /subdirectory/) results in "Path does not exists."
I've experienced similar issue with Scaleway Object Storage and was instructed here to add a line to Panel.ini and it did it. I wonder if similar solution is needed for Storj too?