From AutoCAD 2021, the module is removed from ObjectARX SDK’s redistribute directory and is included as part of AutoCAD 2021.
You can find the module at your AutoCAD installation directory, at my end
It is found at
And, typically I user `where` search tool for quickly finding the modules or files etc, `where` Windows CLI in-built tool.
Another tool I use is `es`, a free CLI utility from VoidTools which is lightening fast
Note: I’m now way endorsing or have any relationship with VoidTools, it is my experience using the tool over a long period.