This snap runs under full confinement, which means it will not be able to access files outside of it's 'home' folder. Normally this would make the app pretty useless, right? So to get around this issue somewhat the snap also consumes the removable-media interface. But it is not hooked up by default. So after installing the snap do:
Snaps are applications packaged with all their dependencies to run on all popular Linux distributions from a single build. They update automatically and roll back gracefully.
Snaps are discoverable and installable from the Snap Store, an app store with an audience of millions.
Snap is available for Linux Mint 18.2 (Sonya), Linux Mint 18.3 (Sylvia), and the latest releases, Linux Mint 19 (Tara) and Linux Mint 19.1 (Tessa).
You can find out which version of Linux Mint you’re running by opening System info from the Preferences menu. To install snap from the Software Manager application, search for snapd and click Install.
Alternatively, snapd can be installed from the command line:
sudo apt update
sudo apt install snapd
Either restart your machine, or log out and in again, to complete the installation.
To install Subsonic, simply use the following command: