Prefix and path for file-based backups has been removed quite some time ago. Instead we use the path configuration from the HANA database itself and are using a fixed prefix "SnapCenter". I don't know exactly with which release the change came in. I looked at a SC4.5P2 installation and this configuration is not there anymore. You said your are using SC4.5, right? Did you make the screenshot for the file-based backup configuration with the same release?
Regards, Nils