These are usually uploaded alongside the .rar files by the original poster. Check the same source (forum, Usenet group, or cloud drive) where you found the RAR.
Use MultiPar or QuickPar to process these files. 🔑 2. Password or "Proof" Paper S2ckb0yDODI2GB.part02.rar
If you are trying to "fix" or "complete" a set of archive parts where part02 might be missing or corrupted, you actually need a (Parchive). These are usually uploaded alongside the