Hi @Sfgirl! Thanks for posting this on our Community.
Have you also added no-reply@dropbox.com to your email contacts, besides checking your email's inbox, spam folder etc?
From what you mention, I understand you don’t have any other devices linked to that Dropbox account. If you do though, check their notifications, as the one-time code may be located there.
In case none of the above work, let me know and we’ll look into this further.
Keep me in the loop.