Board Game Arena

The new tech tile for the expansion - 2 terraforming and building 1 mine, I would like to know if the mine is built for free?
It seems that it requires you to have 2c1o to perform the terraforming and building, but cost you nothing afterward.
Is it a bug or I simply misunderstood its effect?

Why not check the rule book? No need to crowdsource opinions when you can get the truth.