A:Answer Information on box for 'My Passport for Mac' states "Compatibility with macOS High Sierra, Sierra or El Capitan" and also states "Downloadable HFS+ driver to read/write on Windows 10, 8.1 or 7" with disclaimer that "Compatibility may vary depending on user's hardware configuration and operating system".
My new MacBook Pro is running macOS Mojave 10.14.3 and this hard drive was recommended for plug & play use with Time-machine. Have not hooked it up yet.
PDF version of user manual may be downloaded at http://products.Wd.com/docs