How exactly did You download?
Did You try to drag it from the little download-arrow direct into an Archicad-2D-Window?
Or did You try it do download it in Archicad itself in the normal librarytool - dialogue-box - by using the searchfield above?
AC5.5-AC27EduAut, PC-Win10, MacbookAirM1, MacbookM1Max, Win-I7+Nvidia