In order to add adb to PATH on MAC we need to find the Android SDK platform tools path first. You can refere the following blog for finding platform-tools path
Le’s say the platform-tools path you got is: /Users/<username>Library/Android/sdk/platform-tools. You need to run the following command to set the PATH on MAC:
echo 'export PATH=$PATH:/Users/<username>/Library/Android/sdk/platform-tools/' >> ~/.bash_profile
If you are on zsh terminal you need to run the command against .zshrc profile:
echo 'export PATH=$PATH:/Users/<username>/Library/Android/sdk/platform-tools/' >> ~/. zshrc
The adb has been added to PATH on your mac machine now. Restart the Terminal to make use of adb commands.