To enable SSL for your environment, enabling SSL from here you will be able use the diadem.cloud SSL certificate and then click on apply to apply the changes, what is mandate in is there is need to have public IP on nginx.
Installing Lets Encrypt SSL which is free and needs to be installed as an add on in specific instances, for e.g., if there is need to add SSL in Apache Instance then one need to install the application.
Click on Install to add SSL certificate for the domain.
Add the domain name in the field External Domain(s) for which the SSL will be installed.