Microsoft's cloud storage app Box is now available on Windows 10. This version of the app supports all Windows 10 devices excepting phones, which will be supported soon.
All features from the Windows 8 version are included, and some Windows 10 specific features are added as well. Among them: real-time notification center updates, multitasking/resizing functionality, and Live Tiles support so you can pin files and favourites as you please.
You can find Box on the Windows Store with this link. If you're interested in the development side of things, there's an interesting read on the development of Box for Windows 10 over at the Windows Blog here.