New versions of certbot use "snap" to install instead of apt.
Debian and Apache installation instructions here:
https://certbot.eff.org/lets-encrypt/debianbuster-apache
Once certbot is installed, you can add certificates to websites in /etc/apache2/sites-enabled by running certbot --apache.
You can test renewal by running certbot renew --dry-run
You can see if auto renewal is setup by running: systemctl list-timers. Example below:
Remember to add the certificate to zabbix in the 1_Certificate monitoring group!