This issue has been posted here a few times and inevitably comes down to people not reading the instructions or guides in here.
You need to do the following:
1. Move the wow client to the root of your driver (Ex.: c:\wow-mania)
2. Make sure that the file realmlist.wtf is NOT read-only
3. Make sure the client folder is not read-only either
4. Add the client folder to the list of exceptions of your anti-virus
5. Start Launcher as Admin
Check our tutorial here:
viewtopic.php?f=16&t=35 also, check this video:
https://youtu.be/UdeXtu9lcFAIf you still have problems contact me on skype (I can answer faster there).
Skypename: wow-mania.com