Is there a 3.5mm input anywhere in a 2015 XK, I cannot find any, may be you can point me to it. My car only has a USB and an iPod input for Aux.

 

You don't have one. You have the USB and the cRapple interface. What you SHOULD do is put every song you'd ever want on a USB stick and slam it into that USB hole. Good forever.
People who do what you want to do usually buy a Bovee device.
Or, get an old cRapple 30-pin cable and an old ipod. Wee.

 

I have installed an Apple Carplay and need an Aux input for audio, which is currently not working. The output from the unit is a 3.5 Mm jack, which I have connected via an adaptor that ends in a USB male, but somehow it is not doing the job.

 

USB connectors don't like being converted back and forth with audio stuff. You may have a faulty part in there somewhere.

 

If the endgame is playing music from your phone, I'd recommend using the Bovee 1000 interface with the factory iPod connector and using bluetooth audio from your phone. Works great in my 2011 XKR with iPhone 13 Pro Max.

 

I have a piece that i had made for the MOST. it basically takes it over so you do not need AUX and you can use fiber optics. i move on from my 150 so if anyone wants it its for sale in the marketplace. disclaimer i never ended up testing it.