I did via Dropbox web interface.
Next time I will change a folder so large, I’ll use Rclone 
Thinking about what I’m evaluating on this topic, I think I’m going to do a rclone copy of the current folders to the new structure instead of using the Dropbox interface, and then delete the initial files.
In this case, will the copy command run on the server side (without donwload / upload all files)?