Thanks for posting this on the Community, @Raintown!
Have you tried reinstalling the Dropbox app, and you’re still unable to sign in with the one-time code?
If you’re on a free Basic plan, have you made sure you don’t have more than 3 devices currently linked to your Dropbox account?
If not, please send me a screenshot of any errors you’re receiving, and I’ll have a look.
Keep me updated.