There are a log of apps out there that you can use on your phone or tablet to make music or to better learn how to play or read music.
For making beats – this site is not free long term but you can try it for 30 days free. It offers a catalog of royalty free beats, music and sound effects.
Similar to Epidemic sound – they offer a free version
Garage Band OS
This is free to download and use and has a pretty decent library.
Band Lab OS/Android
Lots of options here to use a library or your own music, Free version
More music mixing and beats options here
8 great Rhythm Training Apps here
Best sites, apps and YouTube channels to learn music