High Sierra images are large; a high-speed USB 3.0 drive is recommended for a faster install.
If you typed "RDR" but actually wanted to install High Sierra in or VirtualBox , you need an ISO or VMDK file. top download macos high sierra 10135 image file rdr
Understanding the macOS High Sierra 10.13.5 Image File (.RDR) Format High Sierra images are large; a high-speed USB 3