If level 5; No Captain, nobody to fall asleep.
If Level 2; Motion sensors and loud alarm to wake up the "driver" if he falls asleep.
I believe the Yara Birkeland will initially have an "operator" or two on board.
This being a vessel purpose built for very short voyages, not much in form of facilities for crew comfort is required. Nobody living onboard.
After an initial test period of maybe 1 year, the vessel will have no "operator" on board, but will be remotely controlled from a shore based control centre.
After approx. 2 years it is intended that the vessel will be operating totally autonomous, but with monitoring from the control room ashore.
PS> I sincerely hope that the people developing this project doesn't confuse a vessel at sea with a car on a busy road, with God knows what kind of "idiots" driving the other cars, falling asleep, or be too busy texting to pay attention to what is happening on the road.
Admittedly, they have to consider "numerous" pleasure crafts and WAFIs in that area during the summer season. Best of luck to them.