The B2 download URL from authorization (e.g., https://f004.backblazeb2.com).
The bucket containing the file.
The file name (path) to download.
A download authorization token from b2_get_download_authorization.
URL validity duration in seconds. Defaults to 3600 (1 hour).
The presigned download URL string.
Constructs a presigned download URL using B2's native download authorization. This is not a standard S3 presigned URL but works for B2 download endpoints.