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.
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.