Thanks for the comment, we appreciate it!
Indeed, the fmod lib is not publicly available on the repos, but it is not payed as well. It can be installed through the standalone download of the .so files in the lib's site, however they require you to register, which is unfortunately a boomer hehe. Idk your distro, but in Debian based ones it can be installed like shown here: https://wiki.debian.org/FMOD.
And sorry for the inconvenience :(