Proxmox documentation: https://pve.proxmox.com/wiki/Certificate_Management

Configure ACME

Datacenter ACME
Accounts Click Add
Account Name: default
E-Mail: [email protected]
ACME Directory: Let's Encrypt V2
Accept TOS: ✅
Challenge Plugins Click Add
Plugin ID: proxmox-my-domain
DNS API: DigitalOcean DNS
DO_API_KEY: dop_v1_+++++

Create and submit certificate request

proxmox (node) Certificates ACME
Click Add
Challenge Type: DNS
Plugin: proxmox-my-domain
Domain: proxmox.my.domain
Click Order Certificates Now