If you don’t have it, from a font website — those are pirated copies.
The --INSTALL in your search query suggests you need command-line or GUI installation help. Below are three methods: Windows, Mac, and Linux. Arial Normal Western Panose Font Free Download --INSTALL
Download the .exe (Windows) or .ttf bundle from SourceForge’s msttcorefonts project. Extract to find Arial.ttf . If you don’t have it, from a font