Setting up anything behind a firewall is the kind of thing that requires the skills of a network expert.
If you don’t know how to set up a reverse proxy and/or do something like
You’ll need to find someone who configured the firewall and get them to help. If you don’t have someone like that at hand,
Not unless you know how to get certbot to work behind a firewall. But if you do, then you’re in good shape.
Yes. That’s what you need to do.