if you have those files, you can copy them to the apache2/conf file and you can either rename those files to server.crt and server-ca.crt or modify the apache2/conf/bitnami/bitnami.conf file to use the current name of the files you have.
Please note that if you don't rename the files, you will also need to modify the permissions of them
sudo chown root:root /opt/bitnami/apache2/conf/somename*
sudo chmod 600 /opt/bitnami/apache2/conf/somename*
In case you continue running into problems, you can verify the certificates following this guide
and we also have our troubleshooting guide here
I hope this helps