There are many ways to get ships in Starfield. You can buy them from a Ship Services Technician - same guy you visited for the Chief Engineer (10G) achievement - or you can even board and commandeer ships, before visiting the Ship Services Technician (yup, same guy) and registering them - this will add them to your fleet for a chunk of credits.

On top of that, certain missions like the Mantis mission, will net you a free ship too (check out our Starfield – How to get the Mantis' Razorleaf, one of the best ships in the game, early to net that one), so keep an eye out for them.

To get this achievement, then, you simply have to collect 10 ships. Whether you get them as a reward, buy them and then register them, or commandeer them, it doesn’t matter. Just get 10 and start a proper space fleet.