Lol oops, I just made the same mistake. My game engine uses .ttf so I can't use these. You can keep the $3, I want to support your works :) But perhaps it should be said more explicitly that these are not .ttf and only for Unity.
https://www.angelcode.com/products/bmfont/doc/file_format.html
generic angel code fnt versions of these fonts are here: https://github.com/rakkarage/PixelInterface/tree/main/PixelInterface/Font
works with many font programs and editors
thanks