The Time Crystals originally belonged to Crow (there were only ever 10 of them), but exactly who owned them in 2401 is unknown. What we do know is that the SpaceStation was operated by the Space Marines, as there are signs written in English on board and dead Space Marines littered everywhere after the TimeSplitters arrive. As the Space Marines owned the station, they probably also owned the Time Portal, and the crystals needed to run it.
There is alien writing on the time portal isn't there? Not like the arabic numerals on the uplink and the writing around the spacestation. So I don't think the portal belongs to the marines, it was more likely captured or found (well, in that sense maybe it belonged to them, but they didn't build it).
Where does the number 10 for the time crystals come from? If it runs on crystals, it must only take 1, since it doesn't seem to be needing/using the 9 Cortez goes after. Or are crystals only needed to start
the portal? But what is the reference for this 10th crystal?