Existing index and lifecycle policy

Hello,
I need some help, I've seen many web pages how to configure it but none of them were helpfull.

My existing index (daily index) is

filebeat-exch-8.7.1-2023.05.30

I have created lifecycle policy

2-days

when I want to add this policy to my index I got this

What should I do to fix this? I don't have any Data Streams or Index Templates.

@Alexis_Roberson I am a bit surprised by this response and have a few questions.

When ILM was first introduced I believe it was possible to use it with rollover indices (data streams did not exist at that point) as well as more traditional time-based indices where each index covers a set time period with the time period indicated in the name, which seems to be what the poster is using.

The key to using ILM with non-rollover indices was to not have a rollover action in the policy. This would them if I remember correctly base phase transitions on the indexcreation timestamp rather than the rollover timestamp.

In your response you specify that an index alias need to be created, which I was not expecting. Does this mean that ILM now only can be used with rollover type indices and that traditional time-based indices no longer are supported? If that is the case, when was this change made?

@Christian_Dahlqvist Thanks for providing insight on this. It could be a misunderstanding on my end. Based on the section regarding managing indices without data streams, I drew this conclusion. Let me remove my response as it can be confusing and unhelpful for those viewing this question.