Leo Rover v. 1.6 (as well as older Turtle Rover) uses Buehler motors as the wheels actuators.
Here you have all the useful resources listed in case you need to access the motors specifications.
negative (-) pole of the motor & OUTA of Core2ROS
positive (+) pole of the motor & OUTB of Core2ROS
+5V pin of Core2-ROS
GND pin of Core2-ROS
Mind the encoder magnets are modified to fit Buehler Motors shaft. Internal hole is redrilled to 3 mm (instead of 1.5 mm).