How to host a site on Vercel using cloudfare R2 storage?


I’m quite new to cloudflare, on summary, I’m building a project in nextjs and I want to deploy it on Vercel but I want to use Cloudflare storage (to save a lot of images and files that the users are allowed to upload)
but for what I see is that I need to connect my custom domain in order to access to the files of the bucket, which is not possible because in the cloudflare dashboard it asks me for the DNS, but the DNS are already taken by Vercel… so whats the best way to get/upload the files stored on my cloudflare bucket?, thank you for the help and sorry for the bad english.