You generally have to have a 27" deep cabinet to house a downdraft and a cooktop. If you have that, it's "compatible" per se, but you will still have to install the ductwork to the exterior. And you will be purchasing the least effective vent type that exists, and one of the most expensive.

Overhead venting is always more effective. Look at doing an overhead island vent. It won't be any less money, but it will be 10x as effective.

Thanks for your help. I know it's not the most effective, but overhead is not an option. Ductwork with a remote blower will work very well, as it is a short, direct run out.
I just couldn't find any info on compatibility, and of course they advise sticking with their brand. I will have to modify the back of the cabinet I guess. I do have some dead space, so it should be fine.

Don't do it!!! Compatibility aside, it's just not going to do what you expect it to do. I have a Dacor downdraft system and a Dacor gas cooktop and it's absolutely useless. It sucks the heat from the gas burners, and it's so noisy you can hardly hear yourself think. In the three years I've had it, I can count the times I've used it on one hand. I'm about to do a kitchen remodel, and I'm keeping the cooktop but ditching the downdraft. I'm still not sure if I can vent to the outside because the cooktop is in an island and I can't go straight up and out. But we're trying to figure out a way to vent up, sideways and then out. It'll require a few bends in the vent, and I have an HVAC person figuring it out for me. But I'd sooner have NO exhaust fan than re-install the Dacor downdraft.