Looks like I need to explain this better in the tutorial! All you have to do is pick one of the production buildings (refining node, smelting node, etc.) and toggle them to produce credits instead of resources. There's two toggles on the buildings, on/off and resources/credits.
It seems that 1 raw oil node, 1 ore node, 1 metals node and 1 plastics node are anough for money to go up if you switch everything to sell, no matter how many buildings I have, I don't remember what I did the first time. Note though that inexperienced player can softlock themselves if their maintance cost is higher than everything they can sell. Can I ask what things do have a maintance cost?
Fighter planes should just be in the airstrip, assuming they're in your loadout. The mobile SAM system is a land vehicle. The SAM turret is an upgrade in the base turret. You might be playing an older version, the loadout system was updated somewhat recently so there's a lot more structure now to the unit types you start with.
