How is it possible technically? Did they use any external platforms to implement this?
They have used platform Api with the Apache Thrift framework and Arduino platform
What is Arduino? Is it based on blockchain?
It's not blockchain. Arduino Uno is a development platform based on the ATmega328P microcontroller. Digital inputs/outputs, PWM outputs, analog inputs, 16 MHz quartz crystal, USB and power supply connectors, hardware reset button are available. The Arduino Uno can be powered via a USB connector (+5V) or via an external power supply (VIN) connection. In the second case, the stabilized voltage should not exceed 12V.