Hi,
Honestly, the questions you ask student ambassadors or even admission team members are questions you personally want to benefit from before attending the University. For example, you may want to ask what kind of student support they can provide - during this pandemic, emphasis on student wellbeing and support has been highest. So you may want to ask what kind of services they provide for students regarding this. In the future, should you ever need these services you know what they can offer you.
Also, these student ambassadors are also students at the end of the day. It may be good for some student-to-student talk - you could potentially ask them how they find their classes or what kind of facilities are on campus that they enjoy using, giving you a better idea of what you could use when you finally attend. It's all down to you as the individual to ask any general or private questions regarding attending university. It may be that you are worried or a little bit anxious, so perhaps another student who has been through that initial anxiety can provide that form of solace for you.
I've written general-related things for you to get started on your own questions, feel free to use them or expand on them. But remember it's a good time to get to know what the University is like before moving in.