Okay, this one's a bit different. There are, count 'em, NINE saves attached here:
One called Start with every base and machine ready to go but nothing turned on yet, so you can start any machine yourself and watch it work
Four called Center, one for each planet, where the entire train line is built but the player is still at the center of the world, so you can take the train ride to the corner yourself
Four called Corner, one for each planet, where the player is already at the corner
Fair warning - the Center and Corner saves will devour your RAM. Aquilo and Fulgora can be relatively comfortably handled with "only" 32GB, but Gleba and Vulcanus will happily go past that if you have the extra capacity. I've seen the Vulcanus map cause the game to hit nearly 50GB during the train ride to the end.
There are also two blueprint books attached:
Space Age Megabase is the same book from the Megabase Part 2 video, with a few errata fixed and some new blocks for completeness/end-of-the-world traversal, like lava processing and explosives production
End of the Worlds Machine contains the complete machine circuitry blueprints and all component blueprints, so you can build your own end-of-the-world lines or even attempt to make the journey supplied by a base of your own design
As usual, blueprint books come in the form of text files containing strings; click the "Import String" button on your shortcut bar and paste the file's contents.
Enjoy!