That file is a metadata file, which is created to store the metadata of each schema that you're using in your model. You should be able to recognize the structure of the file name. Your database is called DS-DWH. The catalog is DWH and the schema is DFWSDWH. Its probably a mssql data base.
By writer, are you referring to the report writer cognos role? Do you have the import relational metadata capability? If you expand a node in the metadata tree do you get an error? If you test a table in the metadata tree does it return results?
Where are you trying to save the .fmd file to?
Quotewhich is not even allowing me to access dynamic cubes
Could you elaborate what you mean by that please. Are you not allowed to see them in the Cognos administration console? Not allowed to do stuff in cube designer?