https://starbounder.org/TenantFor this achievement, you need to have had 10 of the unique tenants in a colony at one point. They don't seem to have to have all been there all at the same time, as this unlocked for me while I only had 9 total tenants in my home base.
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You attract colonists from building rooms for them on planets. You need to build rooms that include a door, light source, and a full background. Meaning the rooms are fully enclosed. They have to be fully encased in blocks, meaning the floor or ceiling can't be something like a Wood Platform. Then you'll need to buy a Colony Deed from the Frögg Furnishing store in the Outpost, and place them on the wall of the room. This store will not open until you complete the main quest where you go to the Erchius Mining Facility to get the parts you'll need to repair your ship.
For the unique tenants, you need to place objects of a certain make/biome/material in them, or what the wiki calls "Tags". For example something made from the giant flower petals you can find in the Giant Flowers biomes, their Tag is called GiantFlower.
https://starbounder.org/Tag:GiantflowerSo if you build a room with enough pieces of the Giantflower Tag, the Naturalist Merchant will show up when you put the Colony Deed down.
All the unique tenants are listed in that Tenant wiki page linked above. The Frögg Furnishing store in the Outpost will also sell a different set of furniture each day, which can be used to attract a unique tenant. This changes in real time. The wiki says you can even change your PC's clock to change what the store sells, but I assume that was written for the Steam version, so I have not tried it myself on this Windows 10 version. Then of course you'll be able to pick up different blueprints for certain furniture types, and even just find the furniture pieces out in the game world exploring planets as you play the game. Just be careful if you plan to try to steal furniture or blocks from the NPC villages, as the NPCs will attack you if they see you steal more than 3 times.
Once you have gained 10 unique tenants over time, this will unlock.