works on ubuntu (or a linux distro)

generating ssl certs with letsencrypt using certbot

wget https://dl.eff.org/certbot-auto
chmod a+x ./certbot-auto
sudo ./certbot-auto

//wildcard ssl
sudo ./certbot-auto certonly \
--server https://acme-v02.api.letsencrypt.org/directory \
--manual --preferred-challenges dns \
-d  *.example.com

//non wildcard ssl
sudo ./certbot-auto certonly \
--server https://acme-v02.api.letsencrypt.org/directory \
--manual --preferred-challenges dns \
-d example.com

sudo openssl pkcs12 \
-inkey /etc/letsencrypt/live/example.com/privkey.pem \
-in /etc/letsencrypt/live/example.com/cert.pem \
-export -out ./example-ase.pfx