There is no PBI available in the AppCafe since the Adobe Flash Player should already be installed on your system.
Try this; open up a terminal and type the following commands (one at a time):
That should reset the flash player plugin. Now try restarting your web browser and see if it works for you.
If not, please let us know what web browser you are using. It could be that there is some special issue with that browser, but it is confirmed to work with the "big name" browsers (firefox, chromium, opera).