macOS doesn‘t automagically organize `/usr/local` for you. 

You can do one of the following, depending on the actual need:

 - Put the binaries or scripts directly into `/usr/local/bin`,
 - Put the package into its own directory (under `/opt`, `/usr/local/opt` or wherever you prefer), and run `cd /usr/local/bin; sudo ln -s /path/to/package/bin/* .`. This only works if the binaries introduced by the package have unique names, but has the advantage that you don't need to redo the symlinks if the package gets updated unless `/path/to/package` includes a version number,
 - Add the whole package to `/opt` and the additional bin directories to `/etc/paths.d/name-of-package`.

PS: Finder aliases are **not** symlinks and can‘t be used here.

PPS: The second option is basically what Homebrew does.