You mean it doesn't appear in Plug-in Manager?
Run this MEL command
getenv MAYA_MODULE_PATH
in Script Editor and check the list of paths printed. One of them should contain the file OrnatrixMaya2024.mod, which should point to the correct installation directory.
Ivan Kolev (Software Developer, EPHERE Inc.)
E-mail: ivan.kolev at ephere dot com
Discord: ikolev