The browser may be specifically requesting a certain file type, and the server is unable to deliver the RAR file in that format.
If you are unable to download the file due to a 406 error, try these steps: Download (406) rar
An HTTP 406 error occurs when a web server cannot provide content that matches the specific criteria (such as file type or encoding) requested by your browser. The browser may be specifically requesting a certain
A is a high-quality compressed archive that bundles one or more files into a single, smaller package to save space and speed up transfers. Switching browsers can resolve issues where one browser's
Switching browsers can resolve issues where one browser's "Accept" headers are incompatible with the server. How to Open the RAR File 406 Not Acceptable - HTTP - MDN Web Docs
If you see "(406)" in a filename, it is often a label added by the browser or a download manager to indicate it is the 406th version of a file in that folder, or it could be a manual tag for a specific part of a multi-volume archive . How to Fix Download Issues