A zone is where you will start your slot.
However, it can happen that you get a delivery invitation outside of that zone.
If the pick-up is within the maximum distance, you should ACCEPT this invitation, even if it's not your zone!
Having support cancel it will invalidate your Minimum Guarantee for this slot.
If a delivery takes you outside your zone, you have 1.5x the amount of time you spent on that delivery out of your zone to go back to your zone. See more information on this here.