Thank you for the reply izgerij. The examples in the instructions you suggested show how to leverage Kubernetes to create the container. I was able to figure out how to do this using Docker commands. Poking around in the Secretless Broker docker container I found a folder called certs. I created a container using the -v command and added my ssl cert inside this folder located in the container at /etc/ssl/certs/ and it worked.
example command:
docker run --env CONJUR_APPLIANCE_URL=https://[endpoint.to.DAP] --env CONJUR_ACCOUNT=[DAP account] --env CONJUR_AUTHN_API_KEY=[api-key] --env CONJUR_AUTHN_LOGIN=[host] -it -p 127.0.0.1:1433:1433 -v /host/secretless/yaml/file/location/secretless.yml:/secretless.yml -v /host/certs/location/conjur.pem:/etc/ssl/certs/conjur.pem cyberark/secretless-broker -debug