Next you'll need to engage the drive roller (the cog shaped wheel slightly above of the motor mover unit that engages with the Go-Pod wheels).
To do this, press the center (engage/disengage) and top right (to the right of the green LED that illuminated on the controller in step 2) buttons simultaneously. Hold the buttons in for a few seconds.
You'll then see the driver roller start to slowly move from its position, until it is engaged with the Go-Pods wheels. When it is fully engaged, the small window next to the green arrow on the motor mover unit will be filled yellow.