To access the contents, you will need a file archiver like 7-Zip (Windows) or Keka (macOS). If the file requires a password, it was likely provided within the original blog post context where you found the link.
Some internet puzzle or ARG (Alternate Reality Game) communities use cryptic filenames for downloadable clues. 5DH.7z
Based on the naming convention, this file likely belongs to one of the following niche categories: To access the contents, you will need a