It is not necessarily illegal, but you can download both the software and the PDF of the handbook right here for free.
As long as that seller honors the delivery and the license requirements (ie provide information and access about where to find the source code) then this is (albeit likely frowned upon by many) all good.
Comments
6$ for the software and a handbook as a digital download seems a ripoff (but most probably not illegal) for something you can get for free here
This is the full version and not a trial, free updates for life. yeah, here too
Software: https://musescore.org/en/download
Handbook: https://musescore.org/en/download-handbook
No and yes and no.
It is not necessarily illegal, but you can download both the software and the PDF of the handbook right here for free.
As long as that seller honors the delivery and the license requirements (ie provide information and access about where to find the source code) then this is (albeit likely frowned upon by many) all good.
You'll also notice this seller also offers Open Office. Plus there are two other people selling MuseScore. One says sales benefit a charity.