Same here. I get to the install button in the plarium application's raid game page and click it. Then it briefly switches to display a "downloading" progress bar and then displays the launch error dialogue box.
I'd guess that there is some issue accessing the files for download which is triggering the launch error. It isn't a local PC issue as it doesn't even manage to download anything.
I've also selected an install path for of "c:\Plarium" to ensure no spaces which can cause the issue, as per the Plarium issue blog. Didn't fix it.