Hello,
if you set it to "Windows 64-bit", the compiler creates a x64 enabled installer (with access to the 64-bit Registry branch, access to the 64-bit Program Files folder, etc.). But it is still a native x84 setup application. You need this "Windows 64-bit" option to install native 64-bit applications. To install x86 apps, you set it to the standard "Windows 32-bit" option. To install both (separate) 32-bit and 64-bit type applications from the very same setup.exe, you can use the Hybrid option.
Does this help?
Friedrich