I'm not sure where you've heard it. But at this time, it is not possible for other platforms to crossplay with each other. Unless it comes from the developers directly in an official post, the info you've heard is inaccurate.
I won't confirm or deny that crossplay could happen in the future. It is a possibility, but it will only be after all platforms get to parity. Currently PC version is on 1.3.5.3 while PS4/XB1 are on the equivalent of 1.3.4. The Console versions will have to get to the equivalent version that PC is on before crossplay could be possible. Even when PS4/XB1 does get 1.3.5.3 content, it doesn't guarantee crossplay will happen.