Have you used spotifyd before?
I have never used it but my understanding isspotifyd is not a gui application it is a daemon that runs in the background and you use another device on your network to cast to your PC. Alternatively you can use spotify-qt as a front end to it, there are other frontends but they are not available on Solus.
So spotifyd will not appear in your system menu (it has no .desktop file), only spotify-qt would and either way requires editing config files to function.
I have spotify premium so I will try look at updating it later since the maintainer does not appear to be around any more (last activity in 2021).