"DL16S and DL32S are compatible with iOS 10 or later, Android OS 6 or later.
Interesting - I just got a "you're forked" notice today from Dropbox - no longer supports KitKat as of 6/25 so my two 9" tablets are on their way to obsolescence . It's implied that MF 5.1 for the DL1608 won't run on any of my three iPads (two iPad 2's plus an original iPad Mini stuck on iOS 9.x) and my two tablets (that I use with my XR12) won't be supported . I did just get in today a $40 (shipped) 11" Android tablet that's running Nougat (and even has 5GHz ) so maybe I'm not totally forked .
I know this sucks for you, but on iOS 81% of devices are on iOS11, 14% on iOS10 and 5% on iOS9 or earlier. As a developer, it doesn't make sense to cater to 5% knowing that number will drop far lower in September with iOS12 launching. However, it's a testament that older phones and tablets like an iPad Air 2 or an iPhone 5s are running 11.4. I'm including the links from Apple and Android below, as these are what developers are looking at when they look to see minimum OS to support. In addition, Mackie now has years of data showing them how many (or few) iOS9 devices are being used; my guess is it's a lot lower than 5% and not worth supporting code that was last updated 2 years go - especially when you have 95% of devices running iOS 10 or higher.
https://developer.apple.com/support/app-store/Android, on the other hand, is a scattered S&*t show. Only 5.7% of Android phones are on Oreo, and only 62% are on Marshmallow or higher - but partially because Android didn't specify what needed to be included in phones and tablets to make them more future proof, and partially because the android team doesn't understand hardware and consumers - people aren't upgrading their phones/tablets yearly.
https://developer.android.com/about/dashboards/KitKat and Lollipop is/was a pain in the ass as code needed to be different for each and every flavor of Android by each tablet and phone manufacturer. It's also only 10.3% of installed Android users. So Mackie is being smart and realizing that if they're going to support Android, they need to support the majority of users on the OS version that is easier to code across all Android-powered tablets and phones.
Blame Android, not Mackie on this. I had to work on KitKat compatibility for app-enabled products, and it sucks. While it sucks for us with older tablets, this is the right thing for them to do to keep development costs from spiraling out of control.