Since the RAR format is proprietary, you need specific software to "put together" and review the files:
The file is the second segment of a multi-part compressed archive. To review or access the contents within this specific file, you must treat it as part of a larger set rather than a standalone document. Working with Multi-Part RARs
: An automated solution often used for media server setups to handle archives as soon as they finish downloading. How to Review the Contents