I’ve asked our development team to look into this as I think there’s an issue relating to your old account.
However, ‘/’ isn’t a valid folder name.
In Dropbox, you should have an Apps folder. In there, you should have a Quick File Receipts folder. In that one, you should at least have an Imported folder, but you can also have one with your account number (no slashes). So you could have, in Quick File Receipts:
and so on. Any files put into the related account folder would then be imported into that account.