At the stardock launcher there is a button called settings and an option for edit file settings, when i select edit file settings and error message comes up "cannot find the c:\users\owner\documents\my games\GalCiv3\Prefs.ini file Do you want to create a new file?" what should I do?
You should never click on that option again. It is completely useless.
Notice the GalCiv3 in the path. That was the location used for your data when GalCiv3 was first released. When Crusade was released, the location was changed to GC3Crusade, but the path attached to the button was not updated.
I used the button a lot in the original GalCiv3, then had problems getting my changes to work. I finally found that the location was changed to GC3Crusade after I updated to Crusade when it was released. I filed a bug report about it in a support ticket in August, 2017 (Ticket #XPZ-741-80191 in case anyone at Stardock is interested) and got the reply that they were aware of it and would fix it. It's been 5 years, and it still hasn't been fixed. It probably never will be.
You are getting the error message about not finding the file because you don't have a GalCiv3 directory, probably because you never had the original release of GalCiv3.