I have almost the same set-up with a DXe and a Galaxy S7. So far I have nothing but frustration.
I think you need to connect to the PC first to update the software to version 1.6 before you can use the Android app. I was unable to update using the Spektrum PC based updater software, but I was able to do the update in the Spectrum Programmer PC software. This is all via the SPMA3065 USB to three wire interface cable. After updating the software I am locked out of the PC based software (which seemed very limited in function) because version 1.6 does not support the PC interface, and I saw a warning that it is impossible to go back to version 1.3 after loading 1.6. So next I plugged into my phone with the same cable and a USB to micro USB adapter, the result is that the phone recognized the cable, but there seems to be no connection to the transmitter. So until spektrum releases some updates to their software, I am basically stuck with a transmitter that can only fly one model on the default settings.
I probably works OK if you are buying it with a recent Horizon Bind and Fly product, but this is not a radio I would recommend to someone who might expand their collection or get into building models.