Android Studio on El Capitan - issues in setting up the SDK
This is what worked for me:


Download the command line tools, place them in the SDK folder (e.g., on mac: /Users/user/Library/Android/sdk), unzip there and then add the tools/bin folder to the PATH.
Install the latest platform: in a terminal, execute sdkmanager "platforms;android-25"
Open Android Studio, and go to the SDK Manager (Appearance and Behavior > System Settings > Android SDK)
Click on "Edit", and then select the sdk folder. Then "Next" > "Next" > "Finish".


I hope this works for you too.

Original answer found here: https://stackoverflow.com/questions/42732684/dependant-package-with-key-emulator-not-found-while-updating-android-sdk-and-too

P.S: I'm on Sierra, but I think that's not a macOS problem but Android Studio installer for mac.