.... If you want a specific album from a artist that you dont have you could download copies that other users have ripped. On Linux go ahaead and download Nicotine + and on Mac and Windows theres a app called SoulSeek , theres nothing you wont be able to find honestly. pick the files you want and transfer to your mp3 player. 

//// Setting up Music Server for local access and client playback.
for this we'll use a raspberry pi plug in a flashdrive with your music files and ssh into it.
Step 1 - Install Samba {We'll use the SMB Protocol for this }
Step 2 - #add guest user with -M meaning no home directory / sudo useradd -M guest 
Step 3 - sudo usermod -L guest #// no shell or login.
Step 4 - cd /etc/samba ## make copy of original samba conf file . sudo mv smb.conf smb.conf.bac
Step 5 - sudo touch smb.conf open with vim or nano 
Step 6 - Inside the conf file add these lines. 
[Music] 
path = /mnt/flashdrive
browseable = yes
writeable = no
public = no
valid users = pi, guest 

// this will mount the use the external device mounted on /mnt/flashdrive as the source for the server. (the flashdrive with your music if you want to make it writable change the path and add music to a different directory)

Step 7 - ##add a password for your smb user. sudo smbpasswd -a guest
Step 8 - If you want to add a group of users that could access music share and have read write and execute permission// sudo chmod 775 ~/musicshare // sudo groupadd music / sudo usermod --append --groups music guest // sudo chgrp music ~/musicshare 
Step 8 - sudo systemctl restart smb
Step 9 - Now to access the files on your either android or iOS a client app we could use is called Owl Files allowing us to connect to the server and play our music. I suggest setting up a vpn to connect to your server when your not on LAN instead of port forwarding as its a security risk. On Linux you just mount using ctifs into a directory // sudo mount -t cifs //192.168.1.23/music /mnt/music -o username=your_username,password=your_password,vers=3.0