See https://duet3d.dozuki.com/Wiki/Firmware_Overview#Section_SD_card_structure for the file structure that you need on the SD card. You can find a link there to the files we ship with the Duet WiFi. The same ones will work on the Duet 085 if you put a compatible firmware version on it. Be aware that with recent firmware versions, some Duet 06/085 users find they need to set a static IP address in config.g, otherwise the Duet keeps rebooting when it tries to start up.
You will need to use configtool to generate config.g and homing files.