Step 1 download:

Download Android SDK from the link below:

Step 2 extract:

You can extract it anywhere, but the best place is in the YOUR USERNAME folder root.

Step 3 path environment settings:

Then you need to set the path by copying the below text, BUT edit your username into the path, copy the text into TERMINAL by hitting COMMAND + SPACEBAR type TERMINAL.

export PATH = ${PATH}:/Users/YOURUSERNAME/android-sdk/platform-tools/

Step 4 ADB start:

Hitting COMMAND + SPACEBAR and type TERMINAL, in the Terminal type ADB and hit Enter.