I just bought a bunch of old D&D games. And now i need the code wheels from 1988 in order to actualy paly the games. Either give me my money back, or recreate the code wheels that i do not have.

Normally, there should be a digital version of the code wheel in the "extras" section of your library.
But often the code wheel question in game is modified, so it accepts everything as correct answer.

They should be in bonus materials.

Ah, I think I see what your issue is. The Forgotten Realms collection DOES include the code wheels.

Go to your game library. Click on the collection page, and a list of bonus files should be there. You'll find manuals, code wheels, and possibly some other stuff. Have fun, those are great games indeed!

Indeed.
OP, check the attached screenshot, for what it looks like for Pool of Radiance for instance.

To get there, hover over your username (next to "Support") on top of the screen and in the drop-down menu click on "Games", this will take you to your library.

Once there you should see game cards for, in your case, the 8 titles contained within the archives collection, Vol. 2:

Pool of Radiance
Curse of the Azure Bonds
Hillsfar
Secret of the Silver Blades
Pools of Darkness
Gateway to the Savage Frontier
Treasures of the Savage Frontier
Forgotten Realms Unlimited Adventures

Simply click on each individual game card to show its contents, like in the screenshot.