Help me identify neutral, hot, traveller wire from 3 way switch
The pair is not compatible with your wiring.

There are a variety of 3-way arrangements, with either a) power, switches and lamp in sequence, b) one switch on a spur, c) both switches on a spur, or d) both switches on separate spurs.  This set is designed only to work in the first case, and you have the second case. 

There are plenty of quality 3-way smart switches that will do the job you want done. They will mount in the first location. They will either leave the normal 3-way in the second location, or put a special matching smart switch "remote". 

Send it back

This is cheap Chinese junk that has failed to pass any safety testing. As such it violates NEC 110.2, which requires equipment to be approved.  In practice this means approved by a competent, actual testing lab such as UL.  I'm sorry if you paid a lot for it, but they've been preying rather hard of late on the naïve, and they find it easier to fool people if they set prices nearer to proper equipment.

The usual mark of junkery is a very prominent marking which is totally wrong.  Usually this is the CE mark, sometimes CCC, both almost always faked; but here they don't even bother, and lead with an FCC mark. FCC only pertains to the likelihood of its radio emissions, which certainly is not what your inspector is looking for. 

Your actual wiring

I see 5 cables in this box. 1-4 across the top left to right, and 5 on the bottom.  Cables are multiple wires inside a sheath. 


Cable 1 -> 3-way circuit to remote (spur) 3-way switch.   Wires are


White - Traveler 1 (CCC and SSS)  yellow
Red - Traveler 2 (DDD and HHH)   yellow
Black - switched-hot to lamp  blue

Cable 2 -> Lamp controlled by 3-way switch. 


Black - switched-hot to lamp (KKK) blue
White - actual neutral

Cable 3 -> Lamp controlled by other switch 


Black - switched-hot to lamp red
White - actual neutral 

Cable 4 -> Power (supply or onward, don't care which) 


Black - always hot (BBB and AAA)
White - actual neutral

Cable 5 -> Power (supply or onward, don't care which)


Black - always hot (BBB and AAA)
White - actual neutral



The remote switch has exactly the same "Cable 1" with same wire functions. 

The italic word is the color I would mark the wire if it were me. I like making my job easy. Marking thusly would cause the cables herein to be actually color-coded to function.