Everyone. Submission of the declaration is an integral part of initiating the doctoral examination process. The declaration can be found here: thesis declaration.
All doctoral candidates must submit an electronic version and include the declaration. This applies to all theses, not just those published electronically. If the thesis is published as a book (only exceptional cases), an identical electronic version must also be submitted (Sect. 8 Para. 1b of the Doctoral Regulations).
This enables the doctoral examination procedure to be conducted using the electronic version.