Initially I tried to use the suggested method
In the phone,
1 Go to Settings
2 Go to Apps
3 Go to USB developer mode
None of that was not there.
Then I put the phone into developer mode.
1 Went to Settings
2 Went to About device and pressed Build number three times
2 Phone displayed, "phone in developer mode".
1 Tried to get Xamarin to allow the configuration selection of the device, only Virtual Device and Managed Google Emulators available.
a. Ran and built the program, first the compiler was "building the program"
b. The simulator opened, after twenty minutes,
c. Then displayed " interfacing app to device " waited more time, another twenty min and nothing !
With nothing in the phone.