Sorry that you're unable to launch Lightroom Classic CC.
Could you please try opening Lightroom in root user account on your MAC, so that we can make sure the issue is not related to account permissions? Refer How to enable the root user on your Mac or change your root password - Apple Support
Let us know how it goes.
Many thanks for the reply
I have read the link, where do I open Lightroom using this method?
Can we explore another avenue, loathe to tinker with root account ?
You need to enable the root user account, Lightroom will be there in the application list and you can open it from there.