Well you're talking about an app that was working with "Classic" Mac OS (probably system 7). Files back then had two parts bundled together, a "data" fork and a "resource" fork. The modern MacOS, since Mac OS-X, mostly(*) got rid of that notion, since it was pretty foreign to Unix filesystems (* I'm simplifying a lot).

When you copied the file off the CD, it's possible it just copied the data fork. To check, fire up a unix shell with terminal, and use the "ls" command. If the file is called "foo" ...

ls -l "foo

Ls will show the size of the data fork (in bytes). But ...

ls -l "foo/..namedfork/rsrc"

will show how big the source fork is (in bytes). (ref: http://xahlee.info/UnixResource_dir/macosx.html)

If you used Finder to copy the file it should have all of it, but "cp" and some other utilities would copy just the data fork by default.

And now ... you'll probably want to use a "resource fork editor" to pull apart the pieces. Apple used to call this "resedit" but now you'll probably want to use something like ResKnife (from sourceforge.net). Alternatively, you can install Xcode and use the DeRez command line tool to get to the pieces Some background: https://en.wikipedia.org/wiki/Resource_fork

But .. you might be more than casually interested in Sheepsaver.

https://sheepshaver.cebix.net

It's an emulator that will (with appropriate disk images) let you boot Classic Mac OS and run your app. I've not run it for years, but it worked pretty well when I tried it last (pre-Catalina, so I don't know if it works anymore). The github page for it is active, so I'm guessing it works still

https://github.com/cebix/macemu

Good luck! Be sure and wear a decent mask, the dust flying off these old apps can get pretty nasty

I'll give this all a shot and see what happens.