Is the 16 km run competitive? Or is it open to everyone?

The 16 km is competitive and is called S1 Sprint:

Course along the Rilke path. To participate, you do NOT need a doctor’s certificate and you register online.
Even 6 and 13 km are non-competitive and open to everyone.
Percorso along Mount Ermada. You do not need a medical certificate and you register at 8.00 am on January 6.
To know the difference between S1 Sprint and 6 and 13 of the March of the Bora, read here