Error while connecting to VM on GCP

Hi, I am getting the following error while connecting to VM on GCP:

You are now logged in as [srilakshmiimhskalirs@gmail.com].
Your current project is [hf-flax]. You can change this setting by running:
gcloud config set project PROJECT_ID srilakshmiimhskalirs@cloudshell:~ (hf-flax) gcloud alpha compute tpus tpu-vm ssh forbid --zone europe-west4-a --project hf-flax
SSH: Attempting to connect to worker 0…
srilakshmiimhskalirs@34.91.79.115: Permission denied (publickey).
Retrying: SSH command error: [/usr/bin/ssh] exited with return code [255].
SSH: Attempting to connect to worker 0…
srilakshmiimhskalirs@34.91.79.115: Permission denied (publickey).
Retrying: SSH command error: [/usr/bin/ssh] ex