I have fond memories of running Samba on CentOS at my first tech job at a university. We only had to support enough infrastructure for a couple hundred people in our department, but we wanted to do it with entirely open-source software. There's no way we could have done that if not for Samba. So thank you for working so hard to make that possible!
Samba 4.11 is scalable to 100,000+ users.
In case you want to give us a try :-).