I see you can purchase starbases in the campaigns, but I don't know what to do with them. I have a borg fleet, and the fleet leader shows "delivering starbase". It won't allow me to attack anybody, and I don't know how to drop off the starbase.
if you're the one who bought the starbase then go to the mission select menu and select deliver starbase. If you're not the one who bought the starbase then the only way for that starbase to be delivered is to go to the mission select menu and click on reject on the ship who bought it.