You can put them in (HDname)/Library/Fonts (for all users of the machine) or (HDname)/(username)/Library/Fonts (for one specific user, to use them you have to log in as that user). You have to restart Archicad after installing the fonts. If that doesn't work, restart the machine. If that doesn't work, something is wrong with the font file you used, or you put it in the wrong place. Or you're using a font manager that hasn't allowed them!
Fonts have to be outline fonts of some kind, either TrueType (.dfont), Open Type (.otf) or Postscript (often withput extension) Old Macintosh bit-mapped font suitcases (no extension) also work, if they contain an outline font as well or go together with a Postscript font. You can also use Windows TrueType (.ttf) or OpenType (.otf) fonts as well without modification, but I'm not sure about Windows Postscript variants.
AC4.1-AC26SWE; MacOS13.5.1; MP5,1+MBP16,1