@JAJ17 I believe what is being described in the documentation you mentioned is that Audience Manager acts as the core engine behind the Experience Cloud and this is what allows the Marketo audiences to then be available in Target, so effectively you don't need an Audience Manager license.
As for where the audience is, I'd assume the Audiences > Audience Library section in Target is the place. Unless someone here can confirm, maybe the Target forum would help
From your description, I'm not entirely sure you are actually using RT-CDP, for which there is a Marketo data source connector.