Hi Mike,
It sounds like you are trying to use UC Surface on this device rather than Qmix-UC.
Qmix-UC does not have an unlock code, or a place to enter one, and there is no desktop version of Qmix-UC.
UC Surface does have these things though, but UC Surface is not designed to be used on a phone or phone-sized device.
It sounds like you need to use Qmix-UC on your LG G4 phone:
https://play.google.com/store/apps/details?id=com.presonus.qmix