I've got 5 Android boxes in the house,
none
of them will stream video in D+, three of them will let me download and play the downloaded file, one won't launch the app and one won't even install (it's 4.4 so meh).
Every other service I use (Amazon, Netflix, iPlayer, YouTube, Zion and streams from my media server) runs fine, just not D+ (I don't have NowTV anymore since my NowTV box died and the app won't run on any of my boxes).
Do I just need a box with a certain newness of Android or are there certified devices? I know I can spend £25 on a firestick but from my 10 minute tinker with (a stock) one a while back they're bit laggy and the control is crap.
The Mi Box 4K supports Disney plus. http://www.walmart.com/ip/Xiaomi-Mi-Box-S-4K-HDR-Android-TV-with-Google-Assistant-Remote-Streaming-Media-Player/677842593