Hey there, {First Name},
I really enjoyed meeting you at {name of event} and learning more about what your organisation does. I would love to connect over a coffee to learn more about your experience and background with {add industry or speciality}.
I currently hold the {job} at {business name}, and I'm extremely curious about how you handle the {add issue} that you brought up in our earlier talk.
Let me know which day and time works best for you. If coffee is not possible, we can always connect over a Zoom (or Google Meet) call; I'm flexible.
Hope you have a great day!
Regards,
{Your Name}