Return of Reckoning

Hello. I'm really very sorry if I'm posting this in the wrong area or anything. I'm not great with forums.
So... I tried to follow along with a guide to install Return of Reckoning, but now that I open up the RoRLauncher, I keep being met with this error:

Could not connect to Login server
System.IO.IOException: The process cannot access the file 'C:\Users\Tom\Downloads\Warhammer Online - Age of Reckoning\data.myp' because it is being used by another process.
at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
at System.IO.FileStream.Init(String path, FileMode mode, FileAccess access, Int32 rights, Boolean useRights, FileShare share, Int32 bufferSize, FileOptions options, SECURITY_ATTRIBUTES secAttrs, String msgPath, Boolean bFromProxy, Boolean useLongPath, Boolean checkHost)
at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share)
at RoRLauncher.Client.SendCheck()
at RoRLauncher.Client.Connect()

I have no idea what I'm doing and I'm having difficulty finding what I need to help me.
If anyone could help me with this, I'd be greatly appreciative.
Please & Thank you.