The installer will enable quotas whenever it can. There are cases where it doesn’t know how or where it requires interventions beyond what the installer can safely do (some kinds of virtualization require changes on the host system for quotas to work, for instance, and network filesystems may require changes on the server or may not be manageable by Virtualmin at all).
Soft quotas do not require kernel/OS support, it’s just a scheduled job that checks usage and sends out optional emails about overages.
This is changing the topic. If @Stegan wants help with enabling quotas on their new Installation, or determining why the installer failed to enable them, there needs to be a new topic for it.
This topic is about a system that previous was somehow reportedly showing disk quota features on the Edit Virtual Server and Edit Users pages without having disk quotas actually enabled (which is bug-like, but it’s a bug OP wants). So, we’re trying to figure out what they were seeing and how to make things work the way they want (which I think Soft Quotas does, but we’re waiting on follow up).
I’m also having the same issue. Deployed a vanilla Ubuntu 24.04.3 LTS from Azure Marketplace today. Also running ext4. I tried installing linux-image-extra-virtual and rebooting but that didn’t solve it. Let me know if I can assist in providing any additional details.