For good music notation software, you often have to dig into your pocket or there is a limitation in the number of parts you can work with. That does not apply to MuseScore. In the distant past (2010) we already looked at the first version of this beauty on this site, but an anonymous tipster reported that the program is now ready for version 3. In recent years MuseScore has grown into a very mature program that really has everything on board that a composer could wish for. You can also immediately hear what you write via the built-in synthesizer.
MuseScore you can here to download.
Click the link above to download for free MuseScore – Music Notation Program