Beginner assembly Rover

Good day. I need help, I have a Pixhawk 2.4.8 controller and a Sabertooth 2x12a controller and 2 motors as in the photo, I want to connect it using one 4500mAh - 6S - 22.2V battery, how is it possible to do this? To use only one battery in the rover? Will the Pixhawk controller burn out of the 6s battery?

You need a Power Module for the Pixhawk. A google search of “pixhawk power module” will find many.
More info here. It’s Copter but applicable:
Powering Pixhawk

The power module is also a Power module gm v1.0 model supports only 4s , do you think one 4s battery is enough for two Pixhawk and Sabertooth modules, so as not to load the rover and put two batteries?

There are many factors that would determine that. Just get a 6S capable Power Module if you want 6S power.