You can add music to your mashes if you have a Pro subscription.
To do it, follow these quick steps:
To create a mash, tap the Play button at the bottom of your project's screen.
Select "Music" from the mashing options. The options row scrolls sideways, so swipe along it to reach Music.
Tap a track to apply it — it starts playing over your mash straight away. Tap a different one if you change your mind.
Once you've found the track you want to use, adjust the volume and tap "Done."
iOS app
Android app
If you receive a copyright claim when uploading a mash using the tracks provided by us, please take a look here to learn what you can do.