I tried the files_external_dropbox app and almost got it running but now I am stuck.
The app is active and I correctly configured the dropbox API.
When I hit “grant access” an error msg pops up:
Error configuring OAuth2
Step 2 failed. Exception: Error fetching OAuth2 access token, message: ‘invalid_client: The OAuth client was not found.’
The dropboxv2 entry turns green and the folder shows up in my nextcloud files. However the content of all folders in the dropbox is empty (although they are in fact not).