With a few steps this is how you can install a let's encrypt SSL on hostname with DirectAdmin CP
Step 1
Login to your server via putty and use the following commands
cd /usr/local/directadmin/scripts
./letsencrypt.sh request_single your.hostname.com 4096
Please change the your.hostname.com with your actual hostname.
Once you finish with this you need to enable SSL redirection by default:
cd /usr/local/directadmin
./directadmin set ssl 1
./directadmin set carootcert /usr/local/directadmin/conf/carootcert.pem
./directadmin set ssl_redirect_host your.hostname.com
service directadmin restart
Your hostname now redirects to SSL and it's valid! 😋