Hello @Steve_Spence,
Welcome to this Forum. I assume you are trying to use Debian 12 on OpenNebula 6.10, correct?
Have you followed the information from the docs?
https://docs.opennebula.io/6.10/installation_and_configuration/frontend_installation/install.html#frontend-installation
Please, double check that, and let us know what issues are you encountering to initiate Debian 12 on the current version of the platform.
Thank you!