Flashing on a mac with Arduino IDE

• you need the bottom part (micro usb programmer) and a micro usb cable:
  
• Install ESP32 board in Arduino like so:
  https://randomnerdtutorials.com/installing-the-esp32-board-in-arduino-ide-windows-instructions/
• when installed: select ESP32 Boards → AI-Thinker ESP32-CAM
• select correct port
• click upload

sometimes this works out of the box. If not:

• before Arduino starts uploading: press IO0 button & keep it pressed → press reset button→  release both. The light flashes and it should go to flashing mode
• when Arduino starts uploading ("uploading ....") it should find the device immediately