#1 - Sept. 10, 2014, 12:28 p.m.
We're in the process pushing the latest 6.0.2 PTR Build to the Battle.net app. You should be able to install the 6.0.2 PTR via the Battle.net app shortly.
As a reminder, the Battle.net app is mandatory in order to play WoW, and all updating/installing will now go through it. If you don't have the Battle.net app, get it here! http://eu.battle.net/en/app/
If you have an older version of the PTR build, you may need to uninstall it if your version doesn't automatically update. In order to install the PTR, make sure the Region/Account dropdown box is set to PTR: Mists of Pandaria. Example Picture
More troubleshooting steps can be found in this support article.
Key things to note with this build: