Is it unprofessional to ask (politely) if a place is really hiring?

I'm 16 and have been applying to mainly fast food jobs online, on Indeed. Unfortunately many of these places don't actually have available positions. Like, I applied to Olive Garden and they scheduled me for a second interview, and when I called to confirm, that's when I was told they weren't actually hiring. I just applied to a job that gave me the contact information of the hiring manager. Is it unprofessional if I ask if they have available positions, and what they need filled? I was offered an interview but it was one of those AI scheduling bots.