I suspect there is no reason that MobiLinc HD requires a newer version of iOS.
I have an iPad MD510LL/A - Gen 4 and those are now forever stuck at iOS 10.3.3 and not upgradable.
I was using this with MobiLinc with no problem but it appears that somehow the data got corrupted. I was going to remove and reinstall the app to fix the issue, but you have released MobiLinc to the app store w/o support for iOS 10.
I don't want to spend $400 for a new iPad to use as a dedicated MobiLinc device. Not supporting older devices definitely makes MobiLinc a less attractive option.
The MobiLinc HD symptom:
* run app
* splash screen shows up
* spinny starts spinning
* splash screen disappers
* app does not appear