Of course you can! If you're on the go and have a new song you'd like to add to a playlist you can follow these easy steps.
1. Open the playlist folder you would like to add a song to and click the '+' button in the top right.
2. Then select the Song option. This will open a new song that you can name, add lyrics, add members, and add recordings to.
Note: Currently the functionality to move songs from folder to folder on mobile does not exist yet. So if you need to rearrange songs in your catalog, you'll need to be on your computer.