Log into the Dropbox App console with your Dropbox Account (It need not to be the same account as the Dropbox you want to access)
Choose an API => Usually this should be Dropbox API
Choose the type of access you want to use => Full Dropbox or App Folder
Name your App. The app name is global, so you can’t use rclone for example
Click the button Create App
Switch to the Permissions tab. Enable at least the following permissions: account_info.read, files.metadata.write, files.content.write, files.content.read, sharing.write. The files.metadata.read and sharing.read checkboxes will be marked too. Click Submit
Switch to the Settings tab. Fill OAuth2 - Redirect URIs as http://localhost:53682/ and click on Add
Find the App key and App secret values on the Settings tab. Use these values in rclone config to add a new remote or edit an existing remote. The App key setting corresponds to client_id in rclone config, the App secret corresponds to client_secret