Multi-part RAR files are common for 24-bit/192kHz master recordings or SACD rips that exceed standard file size limits for cloud sharing or email.
Change song and CD information in Music on Mac - Apple Support Nutcracker_Symphony.part3.rar
In some cases, such archives include orchestral parts or full conductor scores in PDF format alongside the audio. How to Access the Data Multi-part RAR files are common for 24-bit/192kHz master