Impressive! Territect "chemistry" is gonna be interesting +1
Please comment the reason if you downvoted!
You have to go to the github page, https://github.com/Rebmiami/Territect. Once you are there, download it, and put the TerraGen.lua file in your scripts folder, which you can find by pressing "open data folder" in the settings you find in the bottom left.
how to download territect manually?