OK, the instructions in post1 above are slightly misleading. I thought you have to get the game into your Steam library and afterwards activate the game. Not true! Rather, you don't have the game in your Steam library. You then select "activate game" and type in the Steam key to a cell. St...

In Steam, the only option l have is to put the game into my cart. Then l have to pay for it with a credit card.

In the instructions above, you buy the game for free, then activate the game with steam keys.

How do l get it into my Steam library?

I still do not understand. The whole idea is to purchase a game on Matrix/Slitherine and then download the game from Steam. 1. The game is published by Matrix/Slitherine 2. Some time afterwards, the game is published by Steam 3. Register my game on Slitherine 4. Then obtain Steam keys 5. At this poi...