Hi
LandStander23.
You can download planet mods in the
Planet Downloads section.
For downloading the packs, just click on the little square at the bottom of a post (I have provided the Starship User Manual for example)
It should look a bit like this:
For installing these packs, I can recommend searching on YouTube “SFS planet editor tutorial,” some of which may guide you through the process of installing planet packs.
And for getting planet packs on PC, that is currently impossible. It might be possible with the next update, but this is unconfirmed.