It could simply be a private compressed folder created by a user (perhaps someone named "Maj") using WinRAR or 7-Zip.

It might be a shorthand reference to a case file or document archive related to MAJ Law , a specialist firm known for handling motoring offences.

In software and gaming, a file named maj.rar (short for mise à jour , French for "update") is often a compressed archive containing a significant software patch or new version.