Other thing is thast rclone.conf are portable / pastable so you can create it on any machine and just copy it or paste it over.
If you have working token on one node just copy/paste it to another - assuming you are using the same APP ID.
Now when you are re-authorizing in web browser are you seeing the rclone logo? If yes then it means you are using default APP ID.
When using your own client_id and client_secret you should see your name there instead of rclone
For me the best option is to create new dropbox config on my laptop and copy paste to headless server.