Unable to connect to Data Center

[Nekodar]

I'm not at home right now so can't direct you to which executable to run, but steam should not be necessary at all.
See if you can find the Final Fantasy entry on the start screen somewhere, or search for where the ffxiv.exe file is. Not sure which file exactly needs to be run, but if you find it you can try from there.
Based on your latest post, find ffxivlauncher.exe and run that from outside steam. Can also try right-click and "run as administrator", just in case...

Did you uninstall all anti-malware and other such programs or only disabled?

Won't be able to suggest anything more until later today.

[JustcallmeSoul]

found a resolution and fixed the problem turns out on very rare occasions on select AMD cards there is a problem with the opening movie, by changing CutsceneMovieOpening in the ffxiv.cfg file from 0 to 1 i was able to load the game perfectly fine. took me 3 days to find a 12 second fix.