ECC support for consumer-grade (non-Threadripper) Ryzen CPUs is present, but it is not an officially promoted obligatory feature. It means that even though processors themselves have non-buffered ECC support, it is up to the motherboard/BIOS whether that function will be available, and there might still be compatibility issues. Look at this as how you would at an overclocking: you might get the result you want most of the time, but nobody guarantees anything. I know for a fact that (unless some motherboard vendors went above and beyond for no apparent reason) buffered ECC is NOT supported.
As for the unbuffered ECC modules, I'd say as long as you find information on it for your specific motherboard (it may not always be disclosed by manufacturer), you have about 90% chance of it to fit perfectly and require no more than switching ECC on in the BIOS settings. There is, of course, still a small chance of issues arising, since once again, it is not a required feature for consumer CPUs.
