Just copy the ESP8266 QRcode folder to your Arduino 'libraries' folder. I have included an example sketch.
The code is based on qrdquino by tz1: https://github.com/tz1/qrduino
Open Library Manager (menu Sketch > Include Library > Manage Libraries…) then install the following libraries
- ESP8266 Oled Driver for SSD1306 display by Daniel Eichborn, Fabrice Weinberg
- Open Arduino IDE, try examples of ESP8266 QRcode library
