it seems a CPU flags issue. There are many causes for this issue. First of all, on the host you should check if your CPU has virtualization support. Then check if it is enabled in the BIOS. Finally, if all the checks give positive result, you should modifiy CPU option, regarding your VM with cloudlet, in VirtualBox, and set to properly value.
Exempli Gratia: I am in similar situation. I use Openstack to generate a VM where I install Openstack++. My CPU flag setting in Openstack is: cpu_mode=host-passthrough, because I don't care about compatibility with other CPUs.
I am not an expert of VirtualBox, but i think that you have to set something like this in VirtualBox, CPU guest model and/or support to 64 bit guests (I think you need 64 bit OS for cloudlet). You would see if there are known issues with nested-virtualization for your CPU model.
Sorry for too generic answer, anyway I hope this can help you.