Hello Joachim,
this button can be enabled by a Service provider or someone who is able to provide support for his users.
This cannot be done at the moment by OM (to external users, perhaps OM will enable the button for the use in the OM offices).
And the Open source community is too small yet to provide this service.
In my personal opinion, the Open Source community cannot provide commercial support and should allow commercial service providers to make some money with paid services, so that the ongoing development of OpenPetra can be secured by people who are able to make their living with their work on OpenPetra. This is not the case yet, but my dream for the long-term.
I hope this makes sense,
Timotheus