How to use Git on Google Cloud [closed]

We have a free Google Cloud server which stores all our files. We package our code to a war, deploy it on a target server, then it’s extracted and deployed.

We are thinking about using Git – to install the client on our local machines.

Do we also need a repository application such as GitHub or BitBucket? Or, can we only use Git and manage the repository on the cloud server?

Also, we would like to use a CI/CD tool - Circle CI. How can we set it up on Google cloud?