Alternator not working, belt diagram needed?

This is the routing for the 3.6 in the Atlas. I take it the old one stopped charging? If yes, then check the battery monitor on the left inner fender. To do that you need the OE level scan tool to monitor the voltage as well as see if the module is working. There are no real tests without the scan tool.

The module keeps track of the battery voltage and tells the PCM to turn the alternator on and off to keep the battery charged. You could buy a scan tool but unless you plan on using it a lot one that will do the job is close to $1,000.00 or so. There is the VCDS tool from ross tech https://www.ross-tech.com/ but I'm not sure it covers that new of a vehicle.

It's hiding in the negative battery terminal assembly and looks like the image attached. As you have swapped the battery and alternator, I would get a scan tool involved and see if the ECM can control the alternator as it sounds like it isn't able to, and you get no charging as a result. For mechanical testing verify that the 400-amp fuse is not blown and that the 5-amp fuse 18 is good as well. If they are good then grab a test light and connect it to ground, now unplug the battery sensors electrical connection. Touch the test light to pin 2 in the harness connector the red with violet wire. It should light up if the battery is connected. Next touch it to the large battery post on the rear of the alternator, it should light. If the test light turned on both times the 5 amp and 400-amp fuses in box A or B are good. Reconnect the current sensor and use a meter to measure the voltage at the battery. Now turn on the headlights and high heat/AC blower and measure again. Write them down and turn them off and start the engine, measure the voltage again. You then turn on the lights and blower again, If it's charging the voltage the second time should be higher than the first time (fully charged battery should read about 12.6 volts, under the load of blower and lights it will drop to something above 11 volts, with the engine running you should see 13-14 volts at least.