Storage music add bibliothèque

the music added to the roon library from quobuz is added physically or it stays in streaming ?

Welcome to the forum, Bruno.

If you favourite a streamed album then this is added to your library, but is only available from Qobuz; there is no local copy. However, if you purchase and download content from Qobuz this will be available from your local library if you set Roon to scan the Qobuz download folder (Settings > Storage.)