Download "Duet2and3Firmware-3.0.zip" from their github. Do not extract the file.

Upload and install that file through Duet Web Control.

When the install is finished send M115 to verify your firmware version is now RRF v3

Now that your board has RRF v3.0.0 we can proceed with installing the latest version. You should be able to update the firmware by uploading "Duet2and3Firmware-3.x.zip" in DWC and install the firmware update.

The latest release from their github

After you are finished installing your firmware verify RRF, DWC and Duet WiFi Server are the latest versions.

Upload the Duet config files from my github