Based on your other post, your primary machine operating system is Windows 7, right?
spacedesk Windows 7 Primary Machine is not supported any more.
Windows 7 life cycle has expired. Microsoft do not support Windows 7 any more – nor can we.
The current spacedesk Driver for Windows 8.1 can still be installed on Windows 7.
It works on many Windows 7 machines and configurations.
On others it does not.
These cases, we cannot support neither fix any more.