The height I won at giveaway is different from the prize and I already registered in my library.

What should I do If I win a game that cannot be activated in my region, or if I receive a gift or key that does not match the game I won?
You should contact the giveaway creator to return the gift, and to inform them of the situation. If the giveaway creator is able to provide you with a replacement gift or key for the same game that can be activated in your region, then you should mark the gift as "Received". In all other cases, the gift should be marked as "Not Received". When marking a gift as "Not Received" it's recommended that you leave an explanation in the giveaway comments as a reference for both the giveaway creator and our support team. If the giveaway creator is not able to provide a replacement gift or key, they may ask your permission to delete the giveaway.

When should I mark a gift I won as "Received" or "Not Received"?
You should only mark a gift as "Received" when you have both (i) received the exact game described in the giveaway, and (ii) activated that game on the Steam account you used during registration. In all other instances you should mark the gift as "Not Received" one week after the giveaway has ended.

https://www.steamgifts.com/about/faq

First of all, DO NOT mark it as received until u get the right game.
If the creator refuses to provide a working key, you can whether wait 7 days and mark as not received or allow to delete the giveaway.
You did nothing wrong.

Hi,
in this case, this is not your fault.
Talk with the creator and maybe he can give you the correct game.
If he can't, you might agree on deleting the giveaway.
in any case, do NOT mark it as received. You might get suspended in the future for this.

There is no way for you to know what key it is before activating it. So you cant check the game, it is creator's responsibilty to deliver right key. All you can do ask them for the right game if they dont have it, wait 7 days and mark giveaway as "Not Recieved". You can't mark it before 7 days so you just have to wait.

And yeah since you dont have the game in your library you can enter other Age of Wonders: Planetfall giveaways.