Cannot set up guest memory error DO407 chapter 12

When doing the guided exercise I get the following error...

[root@tower webapp]# vagrant up
Bringing machine 'default' up with 'libvirt' provider...
==> default: Starting domain.
There was an error talking to Libvirt. The error message is shown
below:

Call to virDomainCreateWithFlags failed: internal error: qemu unexpectedly closed the monitor: Cannot set up guest memory 'pc.ram': Cannot allocate memory

Looking this error up says that I don't have enough RAM.

Sure enough, I don't

[root@tower webapp]# free -m
              total        used        free      shared  buff/cache   available
Mem:           1839        1216         144          38         478         375
Swap:             0           0           0

Anyway to get more ram? or at least NOT run VMs on the same machine you're running Tower with postgres?