the track is listed as:
“anonymous/gregorian: Salve Regina”, choir concerto in the Dome of Aachen,
Choir of the cathedral of Einsiedeln
Choral Master: Pater Roman Bannwart
Organ: Pater Cornelius Winiger
Cond.: Pater Daniel Meier
I think the “anonymous” expresses that the piece comes out of the monastic tradition.