@matildalove
I might have misread this, so forgive me if I have!
You want to run something on your laptop so you can access certain files and maybe stream your music?
If I were you, I would first install Tailscale on the laptop and the device(s) you want to connect to it, then you can access them easily and safely without having to worry about security issues. I'll be honest, I don't know much about it with custom domains, but mine is set up like http://laptop:8080 or http://fedora:3923 depending on the port I wish to access.
For the server side, I'd look into copyparty (https://github.com/9001/copyparty) which creates a file server, where you can also listen to music files. There are loads of ways to install it.