What you need it to do
WinRAR is an archive utility for packaging and extracting files. First decide whether you need to create a particular format or only open a file someone sent you. Those tasks can have different requirements, and a filename extension does not explain what an archive contains.
Extract with a plan
Place a downloaded archive in a dedicated folder and inspect its contents before opening an included program. Keep source files until you have confirmed that an archive can be read back. Compression is useful for organization and transfer, but a single archive on the same drive is not a separate backup.
Choose the supported edition
Use the publisher’s official download and licensing information. The 5.30 and 32-bit wording in this older address are historical details, not a recommendation for a modern computer. Compare architecture and license terms before installation; a trial and a purchased license are different things.