How To Fix "Failed to expand shell folder constant userdocs"
If you've moved the standard Windows folders (for example to a network share) then the installer may crash with the error "Failed to expand shell folder constant userdocs".
Try running the installer as administrator (right-click > Run As Administrator).
Try using the Portable version instead: https://www.unifiedremote.com/download/other
If you're dealing with network drives, then this article may help: http://www.winability.com/how-to-make-elevated-programs-recognize-network-drives/
If that doesn't help, then the only sure way to resolve the issue is to move your Windows folders back to the default location.