I'm an experienced system administrator, programmer, etc., but not a musician.
My grandson is a beginning piano/keyboard student.
We have a basic Yamaha keyboard from Costco, Windows and Linux computers, and a USB to MIDI adapter.
There are several programs available in the Linux repositories that also have Windows versions:
Frescobaldi
Denemo
Laborejo
LilyPond
MuseScore
RoseGarden
We are looking for something easy for a beginner and will not need any advanced features at this time except maybe Audio or MIDI to score capture.
At this time all we want to do is transcribe his lessons. And practice playing along with a MIDI sequencer at an appropriate speed.
Normally we would ask his teacher. But, he is an old school performance only kind of musician. He doesn't even have any recording equipment is his studio, much less MIDI instrument, or even a computer.