@satishbh Also to add more context to this for others who come across it (using the older version):
https://github.com/june07/nodebb-plugin-cloudstorage/issues/2#issuecomment-526089881
The root cause of the error was having an S3 bucket that wasn't public. The plugin then handled the thrown error by the S3 API incorrectly, which was fixed in:
I found the reason that my bucket wasn't public.