After you have clearly invited someone to partner with you either via letter or in person, follow up with them to thank them for their time. This could also be a good time to directly send them instructions on how to give (like the link to the intern page on the JV website).
Example:
You: Hey Alex! Thanks for grabbing coffee with me yesterday. Like I said, I would be really honored by your support. If you want to give, here is the link on the JV website specifically for my internship.
Alex: Oh, thanks for the reminder! When do you leave again?
You: At the end of May! I’ll add you to my updates group so you know when I’m fully-funded and how the internship is going.
Alex: Sweet! Yeah, add me to the list. I’ll be praying!
You: Thank you!