If you are trying to install a LetsEncrypt certificate in DirectAdmin and you see the below error message:
Please make sure /.well-known alias is setup in WWW server.
, this probably means your DNS settings are not correct. Check your DNS settings; does your domain resolve to a wrong IP? If it does, correct it and try to create the LetsEncrypt certificate again.
You use DirectAdmin for some services (like mail) and not for others (like a WordPress website which you host elsewhere). In this case remember to create the LetsEncrypt certificate ONLY for the services on your DirectAdmin server for the domain.
For example, you have a domain mydomain.com and use DirectAdmin for self hosted email (server mail.mydomain.com), and you use an external service to host your WordPress website www.mydomain.com.
In this case you only create a LetsEncrypt certificate for mail.mydomain.com, and leave all others blank.