Cannot install macOS (IL2CPP) Target Support

Hi everyone,
I just install newest unity 2018.3.8f1, and it was hided scripting backend.
Then I downloaded macOS (IL2CPP) Target Support and installed. And I’m tried because of I was failed.
I need IL2CPP to buil my app but it was not available in unity. So bad.
How can I install IL2CPP in my Macbook?
I’m not a native English speaker, so I’m sorry for every mistake.

Now I already install success macOS (IL2CPP) Target Support, but scripting backend still was hided.