Shared Drive Encryption for /both/ Windows & Apple Mac OS

Sorry if this has been asked & answered before. I couldn’t find an answer.

I’d like to use whole drive encryption for an external WD Passport drive that will be used by either a Windows 7, Windows 10, Apple Mac OS El Capitan and Sierra OS. (not simultaneously of course! but that would be cool)

I thought of using VeryCrypt but would just as well use the WD Security drive encryption if I can pass the drive back and forth between computers.

Any ideas? Thank you!