PDFExplorerExtension is an Explorer property handler that must be registered at system level (HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\PropertySystem\PropertyHandlers), not at user level (HKEY_CURRENT_USER\SOFTWARE\...)
(further details here: https://docs.microsoft.com/windows/win32/properties/prophand-reg-dist)
The only option you have is to convince your admin to install it for you... 😉
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