Hello Dan,
It appears that the issue is due to the older GLIBC version on CentOS 6.10, which G4beamline 3.08 doesn't support as it requires GLIBC 2.17 or newer. Upgrading GLIBC on CentOS 6.10 is somewhat challenging and is not recommended as it can lead to system instability.
A practical solution is to use Docker, which allows you to run G4beamline in a container with all dependencies handled internally.
I hope you're doing well and have a great day.
Kind regards,
Eremey Valetov