1. Open file in Dorico.
2. Choose File > Export > MusicXML to open the Export MusicXML dialog.
3. Choose one of the following file format options (both will import into MuseScore 3 with no issue):
- Export compressed XML (.mxl)
-
Export uncompressed XML (.xml)
4. In the Select flows to export list, activate the checkbox for each flow you want to export.