Once content is uploaded it becomes the property of graalonline and can be distributed with permission by the PWA or Stefan to whomever they wish to allow its use.
Due to the many developers involved in such content its no longer necessary to have the original owners permission since they chose not to proceed with their project and closed it down.
Even though I personally don't feel revival projects are the best way to go as most of them are outdated you just need to put in a support ticket with the request through
http://support.graalonline.com