Comment 4 for bug 1831134

The error message below comes from QEMU

2019-05-30T17:08:05.186659Z qemu-system-x86_64: cannot set up guest memory 'pc.ram': Cannot allocate memory

AS such, what I see here is that MAAS is allowing you to create the VM, but qemu is not... so I think you should investigate why qemu doesn;t allow you to.