I just went online and looked at a video explaining what Plex is... I am so confused .my head hurts!
Plex CAN be very confusing if you start getting into the dirt with it, but that's not how you start.
You start with Plex by using a computer that you leave on all the time. Do you have one?
If so, then just load Plex onto it. That's it. Load Plex. There are a ton of tutorial videos, but really, it's just a program.
Once you have Plex loaded onto a computer, you can then open Plex and select 'ADD LIBRARY' (or something like that) to the 'MUSIC' section, and select the folder where you store all your music.
Plex will then add all that music to it's server. It will continue to scan the folder you designated for new music. So, as you add new stuff, it gets added to Plex.
Now, from almost any phone, smart TV, or smart streaming device (Roku, AppleTV, etc.) you can load Plex onto it. You login with your username/password, and you will have access to your Plex library. Your songs will be there and available to you.
I like Plex for how dead easy it was to setup. Took maybe half an hour total.... maybe an hour. I probably watched 3 or 4 hours of videos that all were basically going through the exact same setup process. After installing it, I wondered why I even bothered to watch any videos.
I did pay for their premium 'Plex Pass' service. This was because I wanted remote access to my videos, which this covered. Not sure how specific it is to the music experience, but I knew I wanted it for my videos. You can sign up monthly, then if you like it, you can buy the lifetime Plex Pass and never be bothered again. That's what I did.
If you have specific questions about Plex, there are a number of users on these forums that use it and have more details than I do about their service.