@dave45056 

Well I figured this out on my own.  I'll post this answer in case anyone is considering this combination.

The Lutron MACL-153M is not a true 3-way switch.  They call it a "Single pole/ Multi-location" switch.  This means it can act like a 3-way but not in the traditional sense (ie:using the travellers and another 3 way switch to complete the circuit).

In the end I bought a mechanical 3 way dimmer to work in this scenario and it works great.  Although I can't control the dimming through the app, at least the light is dimmer and I can control the on-off through the app.

If anyone is interested in this set up; this is the switch I bought:

https://www.amazon.com/gp/product/B0885SQNMQ/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

@dave45056 

I am having a similar problem. I have two Lutron Maestro switches as a 3 way, removed one and connected the Kasa 3 way and left the other end with the Lutron and could not get it to work. So what did you do? You made one end a mechanical switch and the other end a Kasa?

  @dave45056 

I successfully installed an HS210 on the LINE side with a Maestro MACL-153M on the load side and it works perfectly.   I used the original wiring from my old three-way switches.

My first time around I connected up two traveler lines to the HS210 and made the mistake of randomly connecting both the MACL's blue screw to one of them and the brass screw to the other:  that is how things worked with my old mechanical 3way switch that used to be there.... but the MACL is a different beast; it switches electronically rather than mechanically, and as such it needs continuous power and requires a very unique setup to achieve this.     Fortunately, although the setup is unique it only took me about 5 minutes to make the change once I read the MACL instructions on how to achieve this.

When my first install didn't work I went back to the packaging and I noticed two things.  1) there was a yellow wire that came in the MACL packaging, and 2) there were installation instructions (search google for Lutron 0301629b and a PDF for the instructions will come up).   On "PAGE 2"  of those instructions, step 6a and step 9 state explicitly how to use the yellow wire, what wire connects to the blue screw v the brass screw, and how to subsequently manually program the MACL switch to work in this configuration.   It's all rather easy once you realize this and follow the instructions.

In the end, the below is how I wired up my system, and it works great:

HS210 (the side connected to the LINE):

White connected to Neutral

Green connected to Ground

One traveler screw is connected to Trav_Red (a red wire going through the walls to the MACL location)

The other traveler screw is unused

I have a wire nut that connects the following three wires:  LINE (a black wire), Trav_Black (a different black wire going through the walls to the MACL location), and the short Yellow wire that came in the MACL packaging (yes, the Yellow wire that comes in the MACL packaging is intended for you to use on the HS210 side of things).

The other end of the Yellow wire is connecgted to the black screw of the HS210.

MACL-153M (the side connected to LOAD):

Green is connected to Ground

Black screw is connected to LOAD (aka the kitchen canned lights)

Brass screw is connected to Trav_Black (which now carries 120V all the time due to the wire nut on the HS210 side of things)

Bluescrew is connected to Trav_Red

Once I had it wired up like that and turned the power back on at the circuit breaker, I then followed step 9 in the MACL install instructions, and voila the whole system is working great.