Note that as of September, 2015 all Web Active Directory products install natively on Windows Server 2012 and 2012 R2 without any additional configuration needed.

To run a 32-bit web application on Windows Server 2012 and IIS 8–especially when you’re running SharePoint–you need to check an application pool setting as well as run a command to conditionally load an ISAPI module depending on if its a 32- or 64-bit application.

Check out the article below for more guidance and note the key operation is to open a command prompt, switch to the %systemroot%\system32\inetsrv directory, and run AppCmd.exe as follows.

“%systemroot%\system32\inetsrv\AppCmd.exe” set config -section:system.webServer/globalModules /[name=’SPNativeRequestModule’].preCondition:integratedMode,bitness64

You also need to ensure 32-bit applications are enabled for the application pool running the Web Active Directory application and the article points out how to enable this. Once you run the AppCmd.exe utility, you should be able to run your 32-bit application.