"Who logged in most recently?"
Translation:Kiu laste ensalutis?
No, not really. eg. "logged in user" means "ensalutita uzanto"-... "Ensalutis" just without anything added doesn't make sense. "Li ensalutis" means "He logged in" or "Mi ensalutis" means "I'm logged in" or "logged in - if shortly expressed..."
Mi ensalutis = I logged in,
I'm logged in = mi ensalutatas/estas ensalutata.
A (currently/now) logged in user = ensalutata uzanto.
Ensalutita uzanto = a previously logged in user.
"Logged in" (in English) can be past tense, a perfect participle, and a passive participle. That might be where you got confused.