If you are still getting the error "PatchManifestError_DownloadFail" it can be resolved by deleting the manifest file manually which will force the launcher to re-generate the manifest. You can find steps for doing so in the article below.
Did you ever find a resolution to this problem? I have contact support, which gave the above suggestions, none of which have worked. Now I haven't heard back from them in almost 72 hours. Any help you could give me would be greatly appreciated.