Clone master branch from certbot Github repo here
cd in to your cloned directory let's say
Set your domain as an env var
mimimi.fun with your own domain)
./certbot-auto certonly --manual -d *.$DOMAIN -d $DOMAIN --agree-tos --manual-public-ip-logging-ok --preferred-challenges dns-01 --server https://acme-v02.api.letsencrypt.org/directory
Follow the instruction given(add TXT record to your DNS record to verify your ownership). Note that applying a wildcard domain+your main domain without prefix requires 2 challenges to be set, you can add two records one by one(do NOT remove neither before you get your certificates)
If everything goes well, you will have your certificates saved here.
Now go to your web server and set up https 😼