Smart Robot Car Third Wheel

This is the part to replace the third wheel of smart robot car from banggood: https://www.banggood.com/DIY-L298N-2WD-Ultrasonic-Smart-Tracking-Moteur-Robot-Car-Kit-For-Arduino-p-1155139.html?p=JH2514288496201309O3

Instruction of this kit can be found here: https://youtu.be/eKcKdMb_nkQ