Alwin studied philosophy, literature and music in Berlin alongside his friends Engelbert Humperdinck and Hugo Kaun. After his education, he worked from 1910 at the Berlin Court Opera and from 1912 in Bayreuth as an assistant. He then started his career as a conductor in 1913 in Halle (Saale), 1914 in Poznań, 1915–1917 in Düsseldorf and then until 1920 in Hamburg. From 1920 to 1938 he conducted at the Vienna State Opera until after the takeover by the Nazis due to a professional disqualification became unoccupied. Because of his Jewish origin, Alwin had to emigrate to the United States. He worked for the Chicago Civic Opera but after the season of 1939/40, he moved to Mexico and conducted in Mexico City at the Opera Nacional from 1941 until his death in 1945. He also taught at the State Conservatory.
- Walter Pass, Gerhard Scheit, Wilhelm Svoboda : Orpheus in Exile. The Expulsion of Austrian Music 1938–1945, Verlag für Gesellschaftskritik, Vienna 1995, ISBN 3-85115-200-X
- Oesterreichisches Musiklexikon, volume 1, Austrian Academy of Sciences, Vienna 2002, ISBN 3-7001-3043-0
- Susanne Blumesberger, Michael Doppelhofer, Gabriele Mauthe: Handbook of Austrian Authors of Jewish Origin 18th to 20th Century, volume 1: A–I. Edited by the Austrian National Library. Saur, Munich 2002, ISBN 3-598-11545-8