I would say that since it sounds like your cold email was more of a request for an informational interview, and his response was more about getting to know you, it would be good to prepare for both.
I recommend definitely having some strong questions you plan to ask regarding the OneNote team goals and challenges, as well as, what has made you interested in this part of Microsoft in particular. You could also ask questions related to his role as PM and any goals he has in addition to the team goals.
I would be prepared to also talk about yourself and any relevant projects/experiences you have worked on that would demonstrate a good fit for this team, in case this is a question he asks you.
Lastly, also be prepared for some standard interview-type questions (you can refer to the Behavioral Matrix).
In your cold email, if you did not attach a resume since the request was more for information, it is not a bad idea to have your resume with you. If the conversation is leading more toward an interview, you could then introduce your resume.
I hope this helps! Congratulations on hearing back on your cold email and getting possibly more than your ask in return!