Carmilla gets a little snarky in this scene, saying 'the Castle moves around' and that's part of her excuse on why she arrived so late after being summoned.
Aside from the fact it's funny Dracula didn't call her out on her bullshit by pointing out the Asian vampires Cho, Raman, and Sharma definitely had a much longer journey, it does raise the question: Why didn't Dracula just use the Castle to pick up his Generals in the ultimate carpool?
Honestly Dracula is such a bitch that at that point i'm convinced that he doesn't have a big weird ass castle with LOTS of stairs just because he's fancy.
He has it because he can teleport his ass anywhere and absolutely enjoys seeing hunters STRUGGLING TO GET AROUND THE PLACE AND MARCH UP THE DAMN STAIRS FOR HOURS just to kill him.
It's the smallest victories that make it all worthwhile...