: The .7z extension indicates it uses the 7z format , known for higher compression ratios than standard ZIP files.

: The archive likely uses LZMA or LZMA2 algorithms to pack multiple files into a single, smaller volume. How to Access the Contents

: It may contain AES-256 encryption , meaning you might need a password to view the contents.

To open this specific file, you will need an archiver that supports the 7z format: Does 7z compress better than zip? - Microsoft Community Hub