I couldnt even install it. My lazarus wanted a "static" something .inc file that it could not find..
Maybe it is in package-source directory. Open package options and write include directory.
You can use it without install. In this case you have to open package click "compile" than you must create components manually at Form.OnCreate, ie.
procedure Form.OnCreate(..);
begin
ahtmlviewer:=THtmlViewer.Create(self);
ahtmlviewer.align:=alclient;
ahtmlviewer.parent:=self;
//do something with ahtmlviewer yet
....
end;
I never install packages to test it.