The file is a compressed archive created using the 7-Zip utility. What is a .7z File?

If the file was created for security, you may be prompted for a password during extraction. Important Security Note

Since Windows and macOS do not always support .7z files natively, you will likely need a third-party tool:

The format is open-source and free to use without registration fees. How to Open "cashewnails.7z"