WebDAV
You can use SFTP / FTP / WebDAV to move data in and out of a Hetzner Storagebox, relying only on Hetzner's infrastructure, and bypassing the ElfHosted infrastructure.
However, to bulk-transfer files to / from [ElfStorage][elfstorage], you'll need something a little more robust than Filebrowser, so we've added a product which exports all your storage (including Storageboxes and rclone mounts) using WebDAV.
Get ElfHosted WebDAV" 
If you purchase a standalone WebDAV Export, you'll be prompted to choose an initial password (bundled users are not prompted), by running Your username is preset to your existing, ElfHosted, username. Your WebDAV url will behttps://-webdav.elfhosted.com`
You can reset your password using ElfBot, by running elfbot env webdav WEBDAV_PASSWORD=yoursekritpassword
You can test the above with a web browser, but for robust file transfer, use one of the options below:
Desktop File Manager
You'll want to tell your file client (i.e. Windows Explorer or MacOS Finder) to open https://<username>-webdav.elfhosted.com (customized for your own username), and enter your credentials when prompted.
Here are generic instructions for Windows and MacOS.
Windows being windows
Per the rclone docs, to make WebDAV work with basic auth (which is what we're doing), you need to get your hands a little dirty, tinkering with the registry!
Rclone
If you're more comfortable on the command line, or wanting to run long, batch transfers, then using rclone directly may be more suitable.
CLI
Install Rclone on your local desktop, and create a new WebDAV remote using rclone config, like this:
[elfhosted]
type = webdav
url = https://<username>-webdav.elfhosted.com
vendor = other
user = <your elfhosted username>
pass = <your chosen webdav password>
Now you can treat elfhosted: just like any other rclone remote. Run rclone ls elfhosted: to confirm.
Web UI
Install rclone, and fire up the UI, using rclone rcd --rc-web-gui --rc-user=<pick a user> --rc-pass=<pick a pass>
The web-gui should now be available at the url http://localhost:5572 - login using the credentials you picked above.
Either configure the remote via CLI as above, or use the UI to configure a similar WebDAV remote.
Use the Explorer interface to upload/download from ElfHosted.
Expected speed
Note that our WebDAV share is rate-limited to ~5MB/s, or 40Mbit, outgoing, which represents 4% of our total 1Gbps per-node bandwidth. This restriction is in place in order to prioritize more realtime traffic over batch transfers.
A prioritized, higher-rate-limited WebDAV instance is also available, with speeds of up to 150Mbps or ~20MB/s.