To get files (*.mdf and *.ldf) of database hosted under Doka panel:
Login into Doka control panel trough your webhosting provider. In "User menu" navigate to "User -> Managed products -> MS SQL -> Databases -> (Database name) -> Get data and log files".
Default file names will be provided. You can change the names if you want to.
Click "Get files" button.
Both files will be placed to default backup location. You'll be able to access it with file manager or FTP.