To create a zone for your website on your Nimbus server against your Cloudflare account, you first need to create or link to your Cloudflare account

Navigate to the Cloudflare page for your website, you will not be able to set up a zone for sub domains.  

On the Cloudflare page, click the "Set up Cloudflare" button, you should now have 2 options.

You will first need to select your account from the Cloudflare account drop down, this will be linked to the account you have already linked, but may also show other accounts for other people who have been added to the server, who may also have set up a Cloudflare account, you are free to choose any of the available accounts here. 

You will then need to choose how you would like the configuration to be set up, from the Setup type drop down.  The 2 options are Via Nameservers and Via CNAME.

With Via CNAME selected, click the "Create Zone" button.  The platform will then connect to Cloudflare and set up the website for you.  Please note, a CNAME configuration can only be set up on a registered domain.  It does not need to be live on the Nimbus platform, but will fail on a fake or test domain.

If successful, you will be presented with a pop-up modal window that will give you some new CNAME resolvers to update your DNS with

Your new Cloudflare zone for your website should now be set up.