What are the laws regarding deliveries to apartments in a gated apartment community in California?
Most of the gated apartments have codes that they may give to them when they are at the gate. These people among others like the police, fire, paramedics and milk trucks have codes that can let them in the apartments.
Gated communities have policies, not laws. Their policy is probably that the delivery person has to check in to gain access, deliver the package, and check out.
Gated communities typically have resident phone logs so a call can be made. I'm pretty sure there aren't any laws regarding how its done, even in CA where we have laws for everything.