SSH to commissioned Machine

Good day Everyone,

I am new into this environment. I have the current setup using the ZED release on Openstack deployment. all 4 nodes are deployed including the controller (juju-controller).
How ever I keep on running to an issue of : ERROR failed to bootstrap model: cannot start bootstrap instance in availability zone “default”: failed to acquire node: No available machine matches constraints: [(‘agent_name’, [‘f5feabb3-64e8-4593-8bdc-f3dee9c586c2’]), (‘mem’, [‘16384’]), (‘zone’, [‘default’])] (resolved to “mem=16384.0 zone=default”).

I have tried several solutions including this that I have seen several times: https://askubuntu.com/questions/1231070/juju-bootstrap-on-ubuntu-20-04. But I cannot execute this solution because if the juju-controller is in commission state, one cannot ssh into the machine because the OS is not installed yet, right? or is the anything that I am missing?