Just copy the SSD1306 QRcode folder to your Arduino 'libraries' folder. I have included an example sketch.
This code is modified from: https://github.com/anunpanya/ESP8266_QRcode
Modified it to support the Adafruit SSD1306 library
Open Library Manager (menu Sketch > Include Library > Manage Libraries…) then install the following libraries
- Adafruit_SSD1306 (+ respective dependency)
- Open Arduino IDE, try examples of example.ino