certbot should be able to write in /var/www/html/ but if that dir is not available on the host, only on the docker container side you can't validate your domain. I don't use docker so can't advise about how to allow the host to write to the dir inside the docker container.
If AWS Linux doesn't distribute certbot as a package then you could check whether you can install snap there and if you can you could use the certbot snap version... or you could use another client like acme.sh