Seems like Mac/Windows standalone rename was not communicated to the publishing team so this results in an inability to install Windows Target Support on Mac, and Mac Target Support on Windows

To reproduce:

1. Go to http://saihai.hq.unity3d.com/history/
2. Select 2018.1 version
3. Select in example 2018.1.0a5
4. Press "Full Page" link

Expected Result: In "Component Installers Windows" and "Component Installers Mac" you will see that there is Mac/Windows Packages
Actual Result: In "Component Installers Windows" and "Component Installers Mac" you will see that there is no Mac/Windows Packages

Notes:
- This issue appears also on Unity Installer - Mac/Windows Packages is on the list, but you can not install them and you will get the error:

"[2017-11-24 13:40:34] Downloading failed with error for URL: http://beta.unity3d.com/download/6cf28aca202e/MacEditorTargetInstaller/UnitySetup-Windows-Mono-Support-for-Editor-2018.1.0a5.pkg"

- Due this issue you can not build on Windows for Mac or on Mac for Windows

Reproduced on Unity 2018.1.0a2 and 2018.1.0a5
Not reproduced on Unity 2018.1.0a1
Regression on Unity 2018.1.0a2