It's on Soundcloud and there are a variety of extensions/apps/etc you can use to download from that:

https://soundcloud.com/aivisura/steven-universe-stronger-than-you-feat-estelle

For Chrome the one I use is https://chrome.google.com/webstore/detail/scdl-soundcloud-downloade/ojobkikmpgjpebmicbjoofagfedgbmld?utm_source=chrome-app-launcher-info-dialog

Pretty much all of the show's music is on Soundcloud at either the above or here: https://soundcloud.com/steven-universeonsc