invalid_request: The provided value for the input parameter 'redirect_uri' is not valid. The expected value is a URI which matches a redirect URI registered for this client application.

[abc2006]

Hi,
unfortunately i had a problem with your installation manual:

For Redirect URL (optional) add the following URL http://path/to/nextcloud/index.php/settings/user/externalstorages (Replace http://path/to/nextcloud/index.php with you valid Nextcloud installation path, ensure that you don't leave index.php in the path. Example: https://nextcloud.myserver.com/settings/admin/externalstorages)

actually, i had to enter
https://nextcloud.augof.space/index.php/settings/admin/externalstorages
as URI to get my onedrive-App working.
So i assume that the hint of "ensure that you don't leave index.php in the path" is not always correct.

As second suggestion you could change the Path in the lower section:

On Nextcloud
Copy Client Id and client secret then Go to Nextcloud /settings/user/externalstorages and Add a new storage OneDrive

to /settings/admin/externalstorages

so the manual gets more consistent.

Last but not least i suggest to rename the
Secret ID to "Value" and the Client-ID to "Application (client) ID" as its named in azure portal.
This would make the targets way clearer for beginners.

Thank you very much for your work
Stephan