How to install SSL on Kobotoolbox

Hi. I have been struggling to install SSL on my Kobo. I have a publicly accessible domain. I am running my Kobo on EC2. Port 80, 443, and 8080 are open. When I am prompted to enter 1 to auto install https with let’s encrypt, I get the following error for all three subdomains.
Fetching http://kc.[mydomain].org/.well-known/acme-challenge/qzaV69P7Q4wIGsWfGkPxnIUDs_bcA8xTulfETW3ua4g: Connection refused
Fetching http://kf.[mydomain].org/.well-known/acme-challenge/UT9tMvEyDlzIVr-cXOjp7WrOWUjuzqIkvQU7I_3Qe9M: Connection refused
Fetching http://ee.[mydomain].org/.well-known/acme-challenge/FqlkFsuO9GRJ7UTIjomapco4-Qx88f_hLp09nNUFtQo: Connection refused

How can I resolve this issue.

Besides Let’s encrypt, I have a wildcard SSL certificate for my domain as well. How can I use that if let’s encrypt can’t work.