If you do not have a Steam account, you will need to download the client from the official website, install it and then create your account. Once you are logged into your account, click on "Add game" in the bottom left corner and then on "Activate product on Steam". After a few clicks on "Next", you can finally enter your CD key, the game will automatically be added to your library and the download will begin.
Download your game on Switch with the Nintendo eShop
Yono and the Celestial Elephants
This is Nintendo's download platform. After buying a Nintendo Switch game, you will receive a download code. Start the Nintendo eShop from the Home menu, select Settings/Other, and then tap "Redeem Download Code" to enter your 16-diogits code which will allow you to download your game.
×
CD key to use on the GOG GALAXY client to download your game.
Yono and the Celestial Elephants
To activate a game you download on GOG Galaxy, open the application on your computer, log in to your account, click on the menu icon, and then select "Game Codes". Enter the game code in the appropriate field and click "Continue". Once the code is verified, the game will automatically be added to your GOG Galaxy library where you can download and play it.
answering the message of 
