Ok, I was told that this was the place to put this topic. haha.
I bought the game Minecraft. and I downloaded the Minecraft launcher and the Minecraft_Server. I had to download it at the Library since we didn't have internet at the house.

At the house I pressed login without typing in my password so that "play offline" would pop up, but it wasn't pressable but said next to it "not downloaded". At the library I played it already cause I read that if you play it once online you don't have to be online the next time you use it.
So any idea how to make it work?