I believe there is not such a report (as yet) in DocuWare from my research into this. The closest you get is in audit reports (provided you have "User Login/Logout" tracked) in the Organization Report which would show active users and their activities but it is not a full user access audit by any means.
Have you searched through https://docuware.uservoice.com/ and added your vote to any submitted features around user reporting? I am currently hunting for similar user audit suggestions.
Otherwise, you could probably put something together using SQL to generate a report out to Excel (I know that doesn't really help unless either you know SQL or have a tame DBA to hand!)
Sorry if any of this is stuff you have already tried / know but thought it worth a mention.
I am trying to locate a calendar / list of DocuWare version support depreciation dates so as to advise customers when current installed platforms REALLY need to be upgraded. For example: When does v6.11 go from primary support (receives regular patches / hotfixes) to extended support (calls can still be logged & addressed by DocuWare support) to end of life (unsupported / professional services may be required).