You can use any kind of songs and music that isn't marked as 'protected' by Apple in your project.
You can make use of music from iTunes by tapping on the library category icon on top left of the Library as well as select iTunes. You require to make certain the songs is downloaded to the device from the Music App (however LumaFusion can not download it like it provides for images as well as videos). As soon as downloaded and saved in the Music App, swipe down on the LumaFusion Library to update the Library and then your downloaded tracks will show up if they are not marked as protected.
Protected music can not be used by LumaFusion therefore is not shown in the Library. This normally includes songs that you paid $0.99 for in ITunes (instead of paying $1.29 for the higher bitrate and also unprotected version). If you subscribe to Apple Music, make sure to download the tracks you wish to use, then you'll have to examine whether they are marked as protected or not. It relies on the specific track.
remember that even music you have actually acquired will likely be flagged on websites like YouTube, Facebook, Vimeo etc, for copyright infringement so the sensible use your ITunes music could be restricted.
You can also import music from cloud storage
right into LumaFusion. faucet on the ... switch at the top left of the library, then tap on Import Media. You'll be able to pick audio files(mp3 m4a, caf, aiff) files to Import. These will appear in the Imported category in the collection.
ultimately, from other applications (GarageBand for example), you can pick an audio documents or music task, faucet on the Share button, and select LumaFusion. The data will certainly be opened in LumaFusion and included in the Imported category.