Hey @soiguessapplpeducksnow, I'd be happy to help, so let's take a look!
Keep in mind, that while you can store your Dropbox folder on an external drive, it's highly not recommended.
Have you tried reinstalling the Dropbox application and choosing the 'advanced' setup during the installation process?
This should allow you to choose the parent folder of the existing Dropbox folder as the location for the new install, so as to merge the folders without re-downloading the files.
For example, if your old Dropbox folder was in: C:\Desktop\Dropbox, you would need to choose C:\Desktop. Feel free to have a closer look at this similar thread too.
If you have any questions, I'll be one post away!