This mod is delivered in single file format and it doesn't require it's own folder, just drop pgs.modpak in your /mods folder.

If you're installing unpacked version, then extract archive to /Starbound/mods, path to pgs.modinfo should be - /starbound/mods/pgs/pgs.modinfo

WARNING!!!
Mod works in multiplayer only if server and all of the players have it installed (same version), otherwise you might lose some of the items.

If you're getting 'dyeengine' related error, then installing dye mod will help you to get rid of it.