Hi @Steven,
Just to add some more details.
I don’t have Mac, but tried on Windows OS, after installing LocalWP and setting up site, by default my setup came with OpenSSL, not LibreSSL (this could be some OS thing), I also got the OpenSSL.cnf file misconfiguration error, the same one as you did.
But right after switching to PHPSecLib as @Bojan suggested:
MainWP > Settings > Advanced Settings
error is gone and I could add sites: