https://www.starwars.com/news/john-williams-attraction-names-star-wars-galaxys-edge
I assume this is the ambient music you'll hear as you walk around the park.
A few more details about Galaxy's Edge in the article:
Bob Chapek, chairman of Disney Parks, Experiences and Consumer Products, announced some major details about Star Wars: Galaxy's Edge today at D23's Destination D: Celebrating Mickey Mouse at Walt Disney World Resort — including the news that John Williams, beloved Star Wars composer, is creating new and original Star Wars themes exclusively for the land. Star Wars wouldn't be Star Wars without Williams' incredible, sweeping scores; getting to hear new work from him at Galaxy's Edge has us all the more excited.
I assume this is the ambient music you'll hear as you walk around the park.
A few more details about Galaxy's Edge in the article:
Indeed, there will be much to do at this exotic outpost, as detailed on the Disney Parks Blog. You can visit a street market in Black Spire Outpost, shop at food stalls where you can enjoy delicacies like blue milk, or visit the Cantina where you can see an old friend, Rex, as well as creatures and characters that are hallmarks of the Star Wars universe.