[SOLVED] How can I use custom domain for Appwrite?

I'm following this docs: https://appwrite.io/docs/advanced/platform/custom-domains But, it cannot be registered in Appwrite console. How can I solve this case?

TL;DR

Developer was having trouble registering a custom domain in Appwrite console, despite following the documentation. The solution was to turn off the proxy on their domain in Cloudflare.