Hey! When i tryied to log-in today i noticed a Gray/white bar that told me
“World of Warcraft is Performing initial setup of required data files. This may take a few minutes. you may also Cancel this process and allow the Launcher to complete installation” And the Download “marker” is paused at like ~60% and it haven’t moved in 3hrs…
I’ve tried the Repair-Tool and Like EVERYTHING, in the “blizzards Help tools section” but nothing there Helped me With it 
Hey, did you have any luck yet?
I had a similar problem. I tried to reinstall the launcher to fix it, but that made it worse, because the launcher would not download correctly. It seems to be connected to my network, because I was able to proceed using my cellphone mobile internet. After reinstalling Battle.net I opened WoW and the ““World of Warcraft is Performing initial setup…” Window appeard again, but it was solved after a few seconds. Afterwards I closed WoW and enabled my “normal” internet again.
Everything works now… Only took like 6 hours to solve over 2 days…
This is probably only a temporary fix, but lets see.
Hi there!
So, there’s a few steps to try to resolve this for you, please do make sure to do them in order!
Firstly, please fully close the Blizzard App, and any Blizzard games, and then uninstall the App as per this guide:
Next, please delete all the Blizzard App files, some of which may be left over after uninstallation, by following this guide:
Finally, please download and install the App again via this link:
Once you’ve done that, please try running it again and sign in! You may find it does a number of updates, but that should hopefully fix things. 
Yours,
Arythwinn