What public key is needed?

Question

SSH

To connect to the site of the payment system, the bank asks to send him a Publick key and a certificate file.
I generated them with the following commands and sent them to the bank:

openssl genrsa -out privkey.pem 2048
openssl req -new -key privkey.pem -out request.pem

But the payment still does not work..
Tell me, please, maybe I didn’t need to generate new keys, but I need to take existing ones on the server somewhere?? The site opens via HTTPS, that is, it already has some kind of certificate ... maybe they need keys from an already existing certificate?

Answer 1

https://certbot.eff.org/
choose your distribution, get your web server
configuration mana.
letsencrypt - will give you a trusted certificate, not a self-signed one.

Answer 2

where are these keys used?
why not ask the bank itself?