Ensure the filename is exactly elultimoduelo2021remuxg36.part29.rar . If it has a "(1)" or a different tag at the end from your browser, the software won't recognize it.
Never move part29 into a separate folder until the extraction is 100% complete.
Ensure you are using the latest version of these tools, as older versions often struggle with large 4K archives.
Because this is a specific part of a multi-volume archive, a blog post about it serves best as a for users who may be stuck during a download or extraction process.