advice for preliminary zoom call with research professor for potential opportunities

hi,

i am a high schooler and I cold emailed a HYPSM computational researcher about his bioinformatics work and he said he’d be happy to chat about potential opportunities for this summer. I’m a high school junior with experience in Python and some prior research internships (which haven't been too impactful)

I have a call with him soon and I don’t want to mess it up. what should I focus on during the conversation to actually turn this into a real research opportunity (not just a one-off chat)? What kinds of questions should I ask, and how do I show I can contribute without sounding like I’m just trying to get something? what should i be prepared for?

Also realistically, what are the chances I actually end up joining this lab from something like this?