Invalid Android SDK directory?

I have been scratching my head here trying to get my android SDK to be recognized by Unity. I can’t for the life of me figure out what unity is specifically looking for. I have downloaded the latest SDK using

$ sdkmanager "platforms;android-27"

but that doesn’t seem to matter to unity as it doesn’t recognize it.
127072-screen-shot-2018-11-01-at-41427-pm.png

sdkmanager --version
26.1.1
Unity Version
2018.2.14f1
OS: Mac OS X
version 10.14

I had the same problem, and could not really solve it. Yet, by uninstalling the sdkmanager and then installing the huge, heavy ‘android studio’ I managed to build. I wish sdkmanager had worked.