Supply units

I cannot configurate to create 1 supply unit, it says that I miss some weapons, but even when I have them, still says I dont.

You can use the feature that is on the screen when you build a unit.
the feature will purchase what you need immediately.

I just used it today and built a large supply unit.

Please try it this way.
If it does not work, let me know, including the name of the world and country.
I will then look into it.