I followed the documentation, even chasing down an older version of OpenVPN/easy-RSA. All were created and uploaded to the AWS cert-manager. The server and client certs show in the Cert Manager interface but when trying to create the Client VPN endpoint the Server certificate ARN does not show in the interface. A search reveals no ARN.
I then backed off and followed the client VPN tutorial video. Downloaded the EasyRSA-3.0.7-win64, followed the instructions but I believe there are some gaps between producing the certs (no configuration of the certs) and the coping for the production directory to the director he uploaded to the directory.