Hi Stephane,
It’s a little hard to tell from what you copied here, but I guess the first thing to say is that if you’re just planning on playing music and don’t need to create notation, you don’t need to install abjad. SCAMP should work just fine without it.
If you do need abjad, we’d need to investigate what the real error is when you try to install it. Not sure if this works on windows, but try going to “Tools > Open System Shell” and then typing in pip install abjad==3.4
. If there’s an error, copy the whole thing that it prints out and paste it here, and maybe we can figure out what’s going on!
(By the way, I see that abjad just came out with version 3.5, so it could be that there’s some issue with that. SCAMP is built to work with version 3.4, so the pip command above targets that version.)