Files like this often require a password found on the original download page. Never download "password unlockers" for these files, as those are almost always malicious.
Often found in threads related to or community-made asset packs/mods. ⚠️ Security Recommendations
Once you have all parts, run a full scan using VirusTotal or Malwarebytes on the extracted folder rather than just the single RAR segment.
To help you further, could you tell me or what you were trying to download (e.g., a specific game or software)?
If any part is missing or corrupted, the entire extraction will fail.