Nvdia ShadowPlay/In-game Overlay is currently enabled in your primary machine, could you please disable it (then maybe reboot) and try again with spacedesk.
if the suggestion above did not help, we also noticed several Indirect Display (same as spacedesk model) devices installed in your system.
In the Device Manager -> Display adapters, you will find these others display adapters:
USB Mobile Monitor Virtual Display
Parsec Virtual Display Adapter
IddSampleDriver Device (3 instances)
If you are not using any of these, can you please try to uninstall these devices one by one then try again with spacedesk.
Probably reboot your machine first after uninstalling each of these devices.