No additional items will be required from Generac, however, to properly connect the transfer switch to the generators battery charger within the generator controller your installing electrician will need to provide a 120V wire from the switch to the controllers T1 connection. This provides the required 120V to the controllers battery charger so it will operate properly.
Please consult with either a "certified" electrician or local Generac installer for installation assistance as they will be familiar with your local electrical code requirements.