PostgreSQL VNET (private site only)

Hi everyone, I've been going through instructions on how to adjust access to PostgreSQl Db only from vnet (private network) for a while now. I'm still spinning in a circle of the same documentation, but nowhere does it say why I don't have the option to add vnet in the security tab.
There are buttons in the documentation that I do not have available 😞
https://docs.microsoft.com/en-us/azure/postgresql/howto-deny-public-network-access 
Please don't anyone know the reason, thanks!