Uconnect Access is a paid subscription service which allows you to download various apps to your phone that will work with your RA3/RA4. These apps provide certain features like the ability to remotely lock and unlock your doors, start the vehicle etc. It also provides access to a wifi hotspot within the vehicle.
RA4 units are Uconnect Access ready, however most vehicles that originally didn't have an RA4 won't have the necessary antenna to access this service. The antenna can be purchased through your dealership or Mopar. The rest of the process involves changing out the factory antenna, and then having your dealer change your build codes to show you have the RA4.
It’s an entirely doable process but sometimes not easily done. The hardest part can be getting your dealer to update the build codes, so that when you call UConnect support to activate it they show you have this unit