I am tinkering with smart home for a while now and before Christmas I remembered that I once used to be an electronic technician - that's more than 25 years ago. However, I wanted to refresh some of my skills. I got the right tools now and so I wanted to dive into the world of Arduinos. I got a starter kit 5 years ago from my company as an Advent calendar - but didn't to anything with it. Though the device that came with it has also Wifi capabilities, I am now playing with a NodeMCU that also comes with a ESP8266 (wifi module). The plan is to create new senors and actors with them.
In general, when you are using a Mac and want to use the Arduino IDE to flash your little computers, you may run into troubles regarding the USB serial drivers (search for "CH340"). On older macOS versions you had to install a driver from a Chinese website - imagine what macOS nowadays does with it... it blocks it until you release it and allow execution. However, using Big Sur right now on most of my machines, the USB serial driver is built-in, so using the Arduino IDE to flash your board shouldn't be a problem, right?
If your IDE is complaining of missing header files during the flash phase, you should take a look into this solution:
It took me deep researches to find a solution in a forum that I wanted to record here for myself.
You don't even have to restart your IDE, flashing should work now.