Apple also competes with Spotify through Apple Music, which has more than 60 million people who use the service worldwide.
Other competitors include rival Pandora and venture capital-backed startups like Luminary that have also created their own libraries of exclusive content.
Greenfield says Spotify must ensure that its users have the best experience finding and listening to podcasts, and supply shows that can't be found elsewhere.
"They have to find content so good that you switch over," Greenfield said.
Ostroff recognizes the challenge in what has become a global business. Spotify, which is in 79 markets worldwide, has been rolling out original and exclusive podcasts in countries like Germany, Brazil, Mexico and Sweden. The company will support its podcast spending by having ads on the programs.
"It's about how do we get big hits on the platform in the U.S. and around the world and create content that's going to really resonate," Ostroff said.
Ostroff was raised in New York City. Her dad worked as a concert promoter and her mom owned a baby items store. She launched her career in Miami while attending college there and working at WINZ radio station. Despite early struggles, Ostroff persisted and became a broadcast journalist, covering local news stories. But reporting wasn't for her.
"News was really a very hard way to make a living and to spend every day covering stories that were so impactful to the world and having the responsibility of needing to be the communicator of what those stories are and the pressure felt intense and overwhelming," Ostroff said. "I eventually moved to L.A. and started to work in entertainment where I laughed a lot and I didn't have that same sense of responsibility, but I did really enjoy the creativity and the ability to tell stories."
Ostroff rose up the ranks in Hollywood, working at companies including Disney, Fox, Lifetime, UPN and the CW network. She led Lifetime Entertainment from 1996 to 2002, when it became a top-rated cable network.
As president of the UPN Network from 2002 to 2006, Ostroff developed hit shows such as "America's Next Top Model," a reality series initially presented by supermodel Tyra Banks that has run for 24 seasons.