

I don’t think you could do that directly in the Caddyfile, but you can create those groups/policies inside VoidAuth and assign them to users there.
The steps would be to (in VoidAuth) create the access group/policy, create the ProxyAuth Domain (protected.example.com/*) with the allowed group(s), make sure the user(s) have that group, then in Caddy add the forward_auth directive to the same route you want to protect.
Then when you go to access that route in a browser it will redirect you to VoidAuth login, or if you pass an Authentication header with Basic Auth (like when using an API) it will use that.
You can try VoidAuth, it is kinda similar to Authelia+lldap. I am the developer and I created it because I wasn’t satisfied with Authelia’s user management. If you decide you want to try it and run into any issues or questions I will try to help :)