With your commander build a factory of any type (Vech, Bot, Air, Naval). Once built build the first thing from the left (which should be a fabber). Once that fabber is built click on it and you should have access to the advanced factory of that type.
Advanced Factories are built by fabbers of the same type. Bot fabricators can build advanced bot factories. Vehicle fabricators can build advanced vehicle factories. etc. And bot fabbers can help a vehicle fabber build advanced vehicle factories.
