They offer both linux and windows applications. Although it could be that for the work they have available at the moment for windows.
But the most likely option is that you don't have the right sub-projects selected. Go into your project preferences, and make sure you have all the sub project checked, as well as "If no work for selected applications is available, accept work from other applications?".
Finally, it looks like they are experimenting with running tasks in a virtual machine. So make sure you have vbox installed, just in case.