As garww wrote, don't kid yourself about not needing protection. Linux isn't affected by
Windows viruses and malware, but it can be infected by Linux viruses and malware. There isn't much of that around, but it does exist - that's why all Linux distros put out occasional security updates. (Distro is short for distributions - every organization who puts out their own version of Linux [Ubuntu, Debian, Slackware, Red Hat, and a couple of hundred more] puts out their own "distro". So you would decide on which distro to use, like Ubuntu). Also, any computer on the Internet can be hacked into if you are careless. As far as free, it may cost you no money to download a distro, but you will spend lots of your precious time getting it going for audio.
On the other hand, there are a lot of fun things about using Linux. I enjoy it.
Ubuntu is very popular and there is lots of user support in their forums. It's not the leanest distro but for a beginner it is probably a good choice, and again there is support. It's also pretty easy to set up, but as with all Linux distros you will need to use the command line for some configuration. If your not afraid of tackling this you might find it enjoyable. Aside from Ubuntu, take a look at the Linux Multi Media Studio (LMMS -
https://lmms.io). Good information there.
To answer your question, when I set up Linux for audio I used a distro called Debian (it's actually the core of Ubuntu). I set up the distro and picked my software so that I could keep my setup lean and unbloated. For my DAW I used Ardour (Harrison Mixbus is based on Ardour). This was a while ago and I used M-Audio Delta 1010s as my interfaces since there were Linux drivers for these units. And that's another thing - make sure the interface you want has Linux drivers. Many don't.
As far as creating music, any Linux distro could be set up for audio. Pick the distro that works best for you. And aside from audio, check out some popular Linux forums for general Linux info and help. If you're going with Ubuntu, start with their forum. Good luck.