Have not found where to deliver the serial key to. After canceling the login solo game starts and it stops where a few recon units are fleeing a pair of tanks and stop in a field next to a river. Nothing I do moves them. Units get selected only while hovering but the selection does not stick. Time keeps passing and nobody moves but the mouse is evidently working, only clicking does nothing.

You can only control the units in blue, not green. There is a tank squad in blue south of the two infantry units. They didn't do a very good job of explaining things in-game as far as tutorials go, and the manual seems to skim over a few basic things. There's a lot of trial-and-error, learn-as-you-go in the campaign in the first 3 missions I've completed.