Looks correct. The Black screw on your two 3ways should be connected to the same black wire bundle. That is your line and then white wire bundle is your neutrals so add the short pigtails you got with the Zooz switches to that bundle. Then load and traveler are the other two wires from your existing 3ways. Don’t believe it really matters which one is which.
In your caption you have “white wire from bundle to ZEN26” and it looks like you pulled a wire out of the bundle.
For the neutrals, you want them all connected together. As @ritchierich said, you should add the pigtail Zooz provided to the white bundle and connect that to the neutral terminal on the smart switch.
If you were to dissect the black bundle, you’d find that it consists of a wire from the Romex that goes back to the breaker plus a pigtail to each switch in the box.
Just FYI, If you end up putting more smart switches in this same box, you can save some room by running the line wire directly to one of the switches, then daisy-chaining to the others. Works great see long as all the switches in the box are powered by the same breaker.
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OK, so it sounds like I don’t actually need to take the white wire in the Romex where the other traveler wires are connected too. I can just leave it in the neutral bundle. I’ll also daisy chain from the other ZEN26 I installed earlier (the right switch) so I don’t have to add another jumper to the neutral bundle.
The triple box is a mess and was hoping I’d be able to install the switch in the double box. It not going to be fun putting that ZEN26 in there. 
Does the same circuit breaker operate all switches in both switch boxes? If so you do have line from breaker power in that box given the single pole switch on the right since it has to have power to work. Assuming same circuit it might work here too.
Triple Box
Left switch is the garage breaker
Middle switch is also on the garage breaker
Right switch is on the kitchen breaker
Double box
Both switches are on the garage breaker
Ok, clarification/emphasis to my previous post given you’ve got switches on two different breakers in the 3-gang box:
Do not daisy-chain power to switches on different breakers. Since your dumb switches will have been pigtailed or connected to their appropriate line wire, just stick to using the wire you took off the dumb switch and you’ll be fine.
I think it’s ok to chain neutrals from different circuits and you’ll probably find all neutral in the box in one big bundle, but I’m less clear on that. Advice, @ritchierich?
Yep. I feel your pain. I’ve got one 3-gang just like it, with switches on two different circuits and I’ve also changed two of the dumb switches to smart.
You can usually shorten some of the wires. The fat bundle of neutrals is a good candidate. Other than that, it’s just a matter of careful cramming.
This is not a good practice and I would avoid it.
I just looked at the Zooz wiring diagram for line and load being in same box and you don’t have enough wires to make this work 
. You would need Black, Red, and White wires between these two switches which you don’t have. So you will need to put it in the 3 gang and follow this diagram:
If you were using the GE or Inovelli with an Aux switch this could work.
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Thanks! I’m gonna have to open up the one 3-gang I’ve got with multiple circuits to see what I did. 
Main issue is this will cause GFIC and Arc Faults to fail since neutral current will/could travel on multiple wires.
That would be bad. I’ll check on it tomorrow. I’ve so far hit a couple of boxes with multiple circuits but have only put multiple smart devices in one of them. It’s not on a ground fault protected circuit, FWIW.
Is my diagram still ok. Only exception is don’t daisy chain the neutral from the other ZEN26 which is on a different circuit? Just use the white jumper to the neutral bundle?
Yes it is fine.
I’m curious: was there a separate, capped, neutral that you used when you replaced the right-most switch in the 3-gang box?
It works! 
I just used the neutral other neutral bundle Now just gotta stuff this mess back together. 
As you can see from the pic I had to use clips for the screws to stay in because the builders stripped the screws. This is not going to be fun.
Thanks for your help!
You can substitute short sheetrock screws. That’s an old electrician’s trick for when you lose the originals.
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Or when the box is pushed too far back for standard screws. I’m finding multiple 3- and 4-gang boxes in my house where the box is angled compared to the sheetrock.
Great! Now that I’ve been educated by @ritchierich, I know that what you needed to do (and have done) is to identify the neutral from the same Romex that is bringing power to your switch.
Since you’ve got two different circuits in this one box and have installed a smart switch on each circuit, the two switches need two different neutrals.
Good luck with cramming!
Good to know! Thanks! Unfortunately, some of the threaded section in the box broke off so the screw didn’t have anything to thread on too which is the reason for some of the clips.
Thanks again for everyone’s help and advice! Saved me $150! 