Troubleshoot flashing Arduino from Ubuntu (as the `ubuntu` user)

TLDR{ Add the ubuntu user to the dialout group when connecting to an Arduino }TLDR My kid was learning to blink leds using an Arduino at a summer camp that he attended recently. He was interested enough to ask if I could buy him an Arduino kit so he could try things at home as well. We went window shopping at the local Micro Center (which opened fairly recently) and found that they did carry a…