Indeed, on my Xiaomi Mi Box S it works.
I will still find out why it is blocking on the Nvidia Shield and if I find a solution I post it.
If someone has a solution, I'm interested.
Thanks for your support ;-)
I have activated developer mode.
But if I activate ADB mode (USB debbuing), my usb key is not recognized and therefore I cannot install APKs.
My box Android is NVidia Shield TV Pro.