Open the dns_updater.ino file in the Arduino IDE.
Download the following libraries:
- Adafruit SSD1306
- Adafruit GFX Library
Add the following board manager in the settings of your Arduino IDE: http://arduino.esp8266.com/stable/package_esp8266com_index.json
Then install the ESP8266 board manager for the wemos D1 mini.
Copy the file secrets.template.h to secret.h and fill in the missing values.