Hello Nicolas Lemarchand,
currently there are no plans to make Office Online editing available for DocuWare On-Premises installations. There are several limitations on the availability of the Microsoft application. Microsoft designed the functionality specifically for Cloud applications and it is currently unknown, if an On-Premises application could actually be usable. And if it would be approved by Microsoft is also unknown.
Regards
Tobias Getz
Team Leader Product Management
DocuWare GmbH