@hfaulk9 wrote:
Do I need to upgrade my plan to expand storage even though the files are on another persons account?
If you're uploading to a shared folder where you have edit access, yes, because you're not uploading to a folder in someone else's account; you're uploading to a folder in your own account and that folder syncs with someone else.
If all you need to do is upload and you won't need to access the files afterwards, ask the recipient to send you a File Request instead.