The composition of richard strauss is now royalty free in most countries (due to differing copyright regulations) since 01.01.2020. More information here:
https://www.br-klassik.de/themen/klassik-entdecken/richard-s... and also here
https://de.wikipedia.org/wiki/Wikipedia:Public_Domain_Day/20...
IMPORTANT: Works by Richard Strauss will remain fully protected by copyright in some territories ( especially in France, Spain and Colombia) after January 1, 2020, due to differing copyright regulations. Please inform before you buy a license. So don't use this song for releases in countries that are still protected. See all copyright lengths here (it should not be more than 70 years, because Strauss died on 8. September 1949):
https://en.wikipedia.org/wiki/List_of_countries%27_copyright...
You can get an additional license for these countries here:
https://www.edition-peters.de/rechteundlizenzen