Bought a second Mac. Want to Sync DropBox with my first Mac. I have DropBox Plus and the folder is way under quota. DropBox on second Mac somehow got another one of my email addresses so it thinks that I have DropBox Basic. Want to change the email address on DropBox for the new Mac so that it knows that I have DropBox Plus and it will sync the folders, obviously. It will not let me do that because it says that the first email address is already taken (obviously! It is the email address I used to purchase DropBox Plus!). I am now in an endless loop. How do I tell DropBox on the new Mac the email address that I used to buy DropBox Plus on the first Mac? I tried verifying the original email address, too. But that did not help either.
It sounds like the second account is signed into the Dropbox desktop application. Try signing out of the app in the preferences page, and then sign into the same account you had on the older Mac device.
This should allow the files to sync down from there onto your new machine.
Jusy give up and switch to a different solution. Dropbox is incapable of syncing your files correctly. I am still another few months away from finally getting all of our business users off of this nightmare of a cloud solution.