I found on the github page ultrasonic sensor could be connected to Pin 13 and Pin 14:

  /**    * Acquiring ultrasonic data    * @param trig trig pin selection enumeration, eg:DigitalPin.P13    * @param echo echo pin selection enumeration, eg:DigitalPin.P14    */

https://github.com/DFRobot/pxt-DFRobot_MaqueenPlus_v20/blob/master/maqueenPlusV2.ts

more info will follow

Sorry, Not helpful, I can not find the Maqueen Plus V2 Pins conected to the micro:bit in the “Education” section.