A Fixed Fare means that you will see the full amount of the fare up-front before you book. No additional fees or tolls will be charged. What you see is what you will pay once you arrive at your destination.
N.B. If you have credits on your account, the credits will be automatically applied to your next personal trip booked and paid through the app using a stored card. This means that the Fixed Fare amount you see in your app when making a booking will be cheaper by the amount of the credit.