/adminmusic subcommands syntax:

• reload: reload the configuration and the sounds files
• player <player>: to see which song player is listening
• play <player> <id>: play a song to a player
• stop <player>: stop the currently listening song
• setItem: set the radio item
• download <url> <destinationFile>: download a song file from the internet and load it
• shuffle|particles|volume <player>: toggle player options
• random <player>: play a random song to a player

How to play song for everyone:

1. Find the ID of the song you want to play to players (open the /music inventory, the ID should be at the end of the song name)
2. Execute /adminmusic play @a <songID>

How to edit the title and description of a song:
Required software: OpenNoteBlockStudio ( https://opennbs.org/)

1. Launch OpenNoteBlockStudio on your computer.
2. Open the NBS file you want to edit.
3. At the top of the window, in the Settings menu, click on Song properties...
4. Edit the fields you want and click OK.
5. Click on the Save button.

How to play songs with more octaves:

• First, setup a mandatory server resource-pack: with more octaves (for instance, this one provided by the dev of NoteBlockAPI).
• In config.yml, enable the useExtendedOctaveRange option.
• Restart your server.

How to make a "region music":
Required plugins: WorldGuard + WorldGuardExtraFlags ( https://www.spigotmc.org/resources/worldguard-extra-flags.4823/)

1. Find the ID of the song you want to play to the player (open the /music inventory, the ID should be at the end of the song name)
2. After that (I assume you already created the WorldGuard region), type /region flag <your_region_name> console-command-on-entry /adminmusic play %username% <ID_of_the_song>
3. The last command to enter is: /region flag <your_region_name> console-command-on-exit /adminmusic stop %username%

How to download a song: (by @MimiKyu)

• 
  
  
  • We will need the URL of the song but the URL has to be .nbs (no mp3 or midi) to achieve that, enter this link:https://opennbs.org/songs/ which will send you to this page that when you scroll down you will see songs (which are all .nbs) and you can even search for the song you are looking for (if it appears or not).
    Once you have seen the song you want, put your mouse pointer where it says download and right click and copy the address of the link and we will have the URL (Long)

• 
  
  
  • As you can see its URL is Long and it will not be able to fit in the game chat, so what you have to do is make the URL shorter, and for that, enter this link: https://xurl.es/ which is used to make the URL small. Once you have it, copy it and enter minecraft.

• 
  
  
  • Once inside the world, use the command that previously taught you (/adminmusic download <url> <destinationFile>). Where it says <url> Put your URL and then where it says <destinationFile> is for you to name it that you want to put to the song within the game. Once that you confirmed that it is already there, you just have to use the command /adminmusic reload and voila, put /music and they will see your music in the playlist, which will enjoy.

If what you want is to create your music or search for more places to have the possibility of finding the music you are looking for, then download Open Note Block Studio. Once downloaded, go to your browser and I will show you the possible sites where you will be able to find the music you are looking for:
1. https://www.midiworld.com/
2. https://bitmidi.com/
3. https://www.mididb.com/
4. https://www.cprato.com/
As you will see, those sounds are in .mid (Midi) format, don't worry, that's why I asked you to download Note Block Studio to transform those sounds .mid to minecraft .nbs. If you do not know how, just follow this tutorial:

and since they are looking at the other David tutorials in case the Studio interests them. Once you have it in .nbs, go to this link again: https://opennbs.org/songs/ and click on the red button that says "Submit a song", once you have your song there in "My Songs" repeat all the steps that I previously taught you and READY, enjoy it