Setting up Ghost CMS on a subdomain of domain managed by Vercel nameserver

Hello, I am currently running a Next.js frontend deployed to Vercel, and I am using the Vercel nameservers to manage the domain.

Now, I want to deploy Ghost CMS to a DigitalOcean droplet on a subdomain, and thus have the admin interface at https://cms.domain.com/ghost

My A DNS records in Vercel look as follows:

when i attempt to install the https://marketplace.digitalocean.com/apps/ghost droplet and set it up, it fails to generate a SSL certificate, and it seems like it cannot use the root domain’s certificate from Vercel if i just provide the IP to the setup script

I am very green with DNS stuff so if anyone knows how i can achieve this setup that would be great.

I am trying to do this because I would not like a user to be able to go to https://domain.com/ghost and be able to see the CMS login. Additionally, if the user goes to https://domain.com first, then to https://domain.com/ghost, a 404 will be returned until the cache is cleared. This is why i am trying to put the ghost CMS on a subdomain.