Hi Jim,
The app does require iOS 10.0 or later, which is a few years old now.
iOS 9.3.5 is the latest version that will run on some older iPad models, so the software for your iPad is probably as up to date as it can be, and therefore you would need to update hardware to in-turn run the necessary software.
I’m afraid there is no fix or workaround, although we have built SQ-MixPad for cross platform compatibility, so if you need wireless control, there are many inexpensive and suitable android devices too.
Thanks,
Keith.