When setting up a Quick Match, there is an option to set the number of bases to capture. For some reason, when trying to set up a Quick Match for the Black Gold Estuary map this option isn't there, and one can only start with one base.

Black Gold Estuary has been configured to not show the number of bases to capture option in the menu, because the map has all bases designated to specific factions in its design. As such, there are no free bases to distribute between factions, so number of bases to capture can't be chosen by player.

It can still be achieved by using the advanced tab and creating a custom start game command which explicitly defines which bases are owned by the factions.