I had faced same issue while working to sharepoint Check whether you have required permission's before generating oauth 2.0, if not try to add the permission's
403 This action will fault on HTTP responses with the 4xx and 5xx status codes. To handle such HTTP responses, enable the 'Fail on HTTP error' property for this action.
This is the detailed error I got
<root>
<error>
<code>accessDenied</code>
<innerError>
<date>2025-07-14T08:29:11</date>
<client-request-id>d73c3b86-fd00-4f89-83e9-e7607fb3ddfa</client-request-id>
<request-id>d73c3b86-fd00-4f89-83e9-e7607fb3ddfa</request-id>
</innerError>
<message>Caller does not have required permissions for this API</message>
</error>
</root>