My understanding of this is that if you have an SEL or R Line then Dynamic Light Assist is standard, and all other models have High Beam Assist.
In both cases, if you have the light switch set to 'Auto', the main beam is automatically set (providing DLA has been switched on in Setup). You do not have to manually set main beam, it is on all the time. If you wish to control main beam manually, don't set the control to Auto, used the Dip Beam setting.
The following is from the VW Technology website, which explains the differences between the two systems:
Dynamic Light Assist
Dynamic Light Assist optimises illumination of the carriageway for even greater safety on the road.
The system with variable road illumination allows the main beam to be left on continuously without dazzling oncoming traffic. This is possible thanks to a masking function which can partially dip the main-beam headlights. The information on other road users and the street lighting is captured by a camera on the interior mirror and relayed to the Dynamic Light Assist system. This significantly improves illumination of the entire carriageway.
Dynamic Light Assist produces a brand new lighting sensation that is always perfectly tailored to the traffic situation.
High Beam Assist
High Beam Assist dips your high beam automatically to improve driver control and safety for both the driver and other road users.
The system is automatically activated when travelling over 37mph with your dipped beams on.
Using a camera built into the rear-view mirror, the system automatically dips the headlights when it detects either oncoming traffic or vehicles ahead.
It is easier than constantly switching from high to dipped beam and safer too, giving you the best view of the road ahead without dazzling other road users.
Steve