Going from a 5.0 Uconnect with manual a/c controls to an 8.4 Uconnect (which has touchscreen climate controls) will take alot more than just a headunit and plugNplay.
@Mpgrimm2 on this Forum is the master at guiding folks with this conversion. In addition, you will require "flashing" your BCM with the proper a/c protocol, along with the AlfaOBD app and an OBDII dongle (like OBD Link). Additionally, you'll need to swap the radio bezel (with a/c controls), an adapter harness, a new a/c module, a cabin humidity sensor and headliner harness, and a cabin temp sensor. I did the 5.0 to 8.4 swap as well for my 2014 and for me it was well worth it! I put in a 2018 UAQ Nav/CarPlay/AA unit (which also needed a usb hub swap and adapter harness) and "flashed" everything myself, with no dealership needed. Hope this helps!