I've tried using \\\\Server\\c$\\Share\\ and also creating a shortcut on the local c: drive and pointing to that but continue to get "file not found" error.
You can use a UNC path as long as the Windows login user for QIE has permissions to that shared drive.
See this related question: https://www.qvera.com/kb/index.php/593/can-qie-connect-to-a-mapped-drive-or-a-unc-path