Once you have the file, follow these steps before extracting the contents:
Avoid downloading .rar files from random pop-ups or "free download" sites, as they are common vectors for malware. 2. How to Open a .RAR File
A popular, free app for Mac users to extract RAR archives. 3. Safety Precautions
You can upload the file (or the download link) to VirusTotal to have it analyzed by over 70 different antivirus scanners simultaneously.
A .rar file is a compressed archive. Windows and macOS cannot always open these natively without third-party software. The original tool for RAR files.