Problem:
Cannot find the command adb in Mac terminal
Solution:
Ensure the environmental variable is setup in $HOME/.zshrc
This is a hidden file, if doesn't exist, can create a new one under $HOME

nano $HOME/.zshrc
Install Android Studio and find out the android SDK installation folder


Add the following code into the .zshrc file
export ANDROID_SDK_ROOT="<your Android SDK path>"
export PATH="$ANDROID_SDK_ROOT/platform-tools:$PATH"
Where

Save the file and you can now access ADB directly