Here is a slideshow quick tutorial on how to set up PayPal to take mobile payments through Taxi Booking's mobile app DriveNot.
It explains how to get Client ID from PayPal that is needed for back end Taxi Booking payment methods PayPal options.
Note that this is just the first step of the process - Obtaining test (Sandbox) credentials. There is a second step required by PayPal for Live mobile payments. Contact us if you need details on how to go Live.