A Windows PC, laptop or Surface tablet can be used as Secondary Machine. 

spacedesk Windows 10/11 VIEWER can be downloaded/installed from Microsoft Store.

spacedesk Windows 7 VIEWER needs to be downloaded from the spacedesk website. It needs setup and installation as shown below.

Run the spacedeskWindowsVIEWER setup installer, spacedeskWindowsVIEWER_v0943_BETA.msi. 

After a successful installation of Windows VIEWER application a shortcut is created on the desktop.