Unfortunatelly, Amazon certificate not working like any other and Bitnami should to know that.
Certificate is not available without Load Balancer (http://docs.aws.amazon.com/acm/latest/userguide/gs-elb.html).
However, steps are not the issue (quite clear explained). For me is complete unclear (unknown) what will be when I will enable it on my already installed Bitnami applications. Can I get automatically HTTPS or I shoudl to do something on my DNS provider, or on Bitnami, or .... whatever else?
It is logical that Amazon will not explain it, as service is "raw". But Bitnami should to explain it as we are using "packed" service/apps (BCH, more precise). To be more precise, I'm quite sure that it must be some "settings" on Apache (as everything is set for HTTP by default) and as Amazon Certificate not working like others, there is probably some "new mix" of instructions included in your reply link, but obviously not like that what can be found there.
So, Bitnami, please be kind and explain it as it should to be explained.