Hello @matttthias ,
If you download the cd-image of 3ds Max 2022, the SDK should be in <cd-image>\x64\Tools\MAXSDK.
Just install the SDK_3dsMax.msi and you are good to go.
We apologize for the 3ds Max installer not exposing an option to install the SDK. This is a limitation of the installer framework we are using currently, and we are working on addressing it.
Another perhaps easier way to get the 3ds Max 2022 SDK is to go to https://www.autodesk.com/developer-network/platform-technologies/3ds-max, scroll down a bit to the section called "3ds Max SDK", and click on the download link.
By the way, did you know that you can navigate to the Autodesk Developer Network site linked above from 3ds Max's Help menu? Help > 3ds Max developer resources > 3ds Max SDK download.
I hope this helps.
Attila Szabo
Product Owner, 3ds Max
Autodesk