In Arduino Create Editor I'm missing Arduino Ethernet board in the menu to select "Other Board an port"
Hopefully that will be fixed soon. Until then you can use Arduino/Geniuno Uno instead.
The only problems with this are: LED_BUILTIN will be set to 13 instead of 9, as it should be on the Arduino Ethernet
The macro ARDUINO_AVR_UNO will be defined instead of ARDUINO_AVR_ETHERNET
The macro SERIAL_PORT_HARDWARE_OPEN will not be defined.
I suspect that only the first one would cause you any problems and it should be pretty easy to notice when the LED isn't working and change the value in the code to pin 9.
@Chano thanks for your report, we will get back to you as soon as the board is back in the menu.
Added to the list, let us know if it works for you, thanks again for your report.