This just means you’ve not told it what board you are using or if you have, it doesn’t know that board so you have to set up the pins - which you have done.
I do macOS, Linux and Windows in that order, so I’m not best placed to comment on the serial ports. Some boards do need prompting before a download. My Adafruit Feather doesn’t need a reset and only shows one serial port. You may want to make enquiries on the Arduino forum / eco-system if no one chimes in here.
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