Anyone able to help me with this issue?

So a friend informed me about this private server and as a hardcoreraider during wotlk i was overth moon but when i start up WoW i updated for patch and then when the file updated it " couldnt find the file" and then got the meessage " The file "C:\Wrath of the Lich King 3.3.5a\WoW.exe" is read only and cannot be overwritten. Please try installing to a different location. (ConflictManager::DeleteFile)"

If anyone can help be much appreciated.

may i add wow loads up just fine to log in screen